Delayed Sleep Phase Disorder
   HOME

TheInfoList



OR:

Delayed sleep phase disorder (DSPD), more often known as delayed sleep phase syndrome and also as delayed sleep–wake phase disorder, is a delaying of a person's
circadian rhythm A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous) and responds to ...
(biological clock) compared to those of
societal norms Social norms are shared standards of acceptable behavior by groups. Social norms can both be informal understandings that govern the behavior of members of a society, as well as be codified into rules and laws. Social normative influences or soc ...
. The disorder affects the timing of biological rhythms including
sleep Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited Perception, sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefuln ...
, peak period of alertness, core body temperature, and hormonal cycles. The diagnosis of this disorder is currently a point of contention among specialists of sleep disorders. Many insomnia-related disorders can present significantly differently between patients, and circadian rhythm disorders and melatonin related disorders are not well understood by modern medical science. The
orexin Orexin (), also known as hypocretin, is a neuropeptide that regulates arousal, wakefulness, and appetite. The most common form of narcolepsy, type 1, in which the individual experiences brief losses of muscle tone ("drop attacks" or cataplexy) ...
system was identified only in 1998, yet it appears intimately implicated in human sleep-wake systems. Evidence for the plasticity of human circadian rhythm cycles has been provided by multiple studies. In one example, several dozen volunteers spent many months underground in a French cave, while researchers monitored their periods of waking and sleeping. Their results found significant divergence between individuals, with most participants settling upon a rhythm of 30 +/- 4 hours. Researchers have speculated that the lack of exposure to natural sunrise/sunset cycles relates many of the symptoms of these circadian disorders to modern habits of humans spending extended periods indoors, without sunlight exposure. Symptom management may be possible with therapeutic drugs such as
orexin antagonists An orexin receptor antagonist, or orexin antagonist, is a drug that inhibits the effect of orexin by acting as a receptor antagonist of one or both of the orexin receptors, OX1 and OX2. Medical applications include treatment of sleep disorders ...
or
melatonin receptor agonists Melatonin receptor agonists are analogues of melatonin that bind to and activate the melatonin receptor. Agonists of the melatonin receptor have a number of therapeutic applications including treatment of sleep disorders and depression. The disc ...
, as well as regular outdoor exercise. There may be a genetic component to the syndrome.


History

DSPD was first formally described in 1981 by Elliot D. Weitzman and others at
Montefiore Medical Center Montefiore Medical Center is a premier academic medical center and the primary teaching hospital of the Albert Einstein College of Medicine in the Bronx, New York City. Its main campus, the Henry and Lucy Moses Division, is located in the Norwoo ...
. It is responsible for 7–13% of patient complaints of chronic
insomnia Insomnia, also known as sleeplessness, is a sleep disorder in which people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, ...
. However, since many doctors are unfamiliar with the condition, it often goes untreated or is treated inappropriately; DSPD is often misdiagnosed as primary insomnia or as a
psychiatric Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry. Initial psy ...
condition. DSPD can be treated or helped in some cases by careful daily sleep practices, morning
light therapy Light therapy, also called phototherapy or bright light therapy is intentional daily exposure to direct sunlight or similar-intensity artificial light in order to treat medical disorders, especially seasonal affective disorder (SAD) and circad ...
, evening dark therapy, earlier exercise and meal times, and medications such as aripiprazole,
melatonin Melatonin is a natural product found in plants and animals. It is primarily known in animals as a hormone released by the pineal gland in the brain at night, and has long been associated with control of the sleep–wake cycle. In vertebrat ...
, and
modafinil Modafinil, sold under the brand name Provigil among others, is a central nervous system (CNS) stimulant medication used to treat sleepiness due to narcolepsy, shift work sleep disorder, and obstructive sleep apnea. While it has seen off-la ...
; melatonin is a natural neurohormone partly responsible for the human body clock. At its most severe and inflexible, DSPD is a
disability Disability is the experience of any condition that makes it more difficult for a person to do certain activities or have equitable access within a given society. Disabilities may be cognitive, developmental, intellectual, mental, physical, ...
. A chief difficulty of treating DSPD is in maintaining an earlier schedule after it has been established, as the patient's body has a strong tendency to reset the sleeping schedule to its intrinsic late times. People with DSPD may improve their quality of life by choosing careers that allow late sleeping times, rather than forcing themselves to follow a conventional 9-to-5 work schedule.


Presentation

People with DSPD generally fall asleep some hours after midnight and have difficulty waking up in the morning. Affected people often report that while they do not get to sleep until the early morning, they do fall asleep around the same time every day. Unless they have another sleep disorder such as
sleep apnea Sleep apnea, also spelled sleep apnoea, is a sleep disorder in which pauses in breathing or periods of shallow breathing during sleep occur more often than normal. Each pause can last for a few seconds to a few minutes and they happen many tim ...
in addition to DSPD, patients can sleep well and have a normal need for sleep. However, they find it very difficult to wake up in time for a typical school or work day. If they are allowed to follow their own schedules, e.g. sleeping from 4:00 am to 1:00 pm, their sleep is improved and they may not experience
excessive daytime sleepiness Excessive daytime sleepiness (EDS) is characterized by persistent sleepiness and often a general lack of energy, even during the day after apparently adequate or even prolonged nighttime sleep. EDS can be considered as a broad condition encompass ...
. Attempting to force oneself onto daytime society's schedule with DSPD has been compared to constantly living with jet lag; DSPD has been called "social jet lag".


Comorbidity


Depression

In the DSPD cases reported in the literature, about half of the patients have had
clinical depression Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive low mood, low self-esteem, and loss of interest or pleasure in normally enjoyable activities. Intro ...
or other psychological problems, about the same proportion as among patients with chronic insomnia. According to the ICSD: A direct neurochemical relationship between sleep mechanisms and depression is another possibility. It is conceivable that DSPD has a role in causing depression because it can be such a stressful and misunderstood disorder. A 2008 study from the
University of California, San Diego The University of California, San Diego (UC San Diego or colloquially, UCSD) is a public land-grant research university in San Diego, California. Established in 1960 near the pre-existing Scripps Institution of Oceanography, UC San Diego is ...
found no association of
bipolar disorder Bipolar disorder, previously known as manic depression, is a mental disorder characterized by periods of Depression (mood), depression and periods of abnormally elevated Mood (psychology), mood that last from days to weeks each. If the elevat ...
(history of mania) with DSPD, and it states that The fact that half of DSPD patients are not depressed indicates that DSPD is not merely a symptom of depression. Sleep researcher
Michael Terman Michael Terman is an American psychologist best known for his work in applying the biological principles of the circadian timing system to psychiatric treatments for depression and sleep disorders. This subspecialty is known as Chronotherapeuti ...
has suggested that those who follow their internal circadian clocks may be less likely to have depression than those trying to live on a different schedule. DSPD patients with depression may be best served by seeking treatment for both problems. There is some evidence that effectively treating DSPD can improve the patient's mood and make antidepressants more effective.
Vitamin D Vitamin D is a group of Lipophilicity, fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and many other biological effects. In humans, the most important compounds in this group ar ...
deficiency has been linked to depression. As it is a condition which comes from lack of exposure to sunlight, anyone who does not get enough sunlight exposure during daylight hours (about 20 to 30 minutes three times a week, depending on skin tone, latitude, and the time of year) could be at risk, without adequate dietary sources or supplements.


Attention deficit hyperactivity disorder

DSPD is genetically linked to
attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...
by findings of polymorphism in
gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
s in common between those apparently involved in ADHD and those involved in the circadian rhythm and a high proportion of DSPD among those with ADHD.


Overweight

A 2019 study from Boston showed a relationship of evening chronotypes and greater social jet lag with greater body weight / adiposity in adolescent girls, but not boys, independent of sleep duration.


Obsessive–compulsive disorder

Persons with
obsessive–compulsive disorder Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which an individual has intrusive thoughts and/or feels the need to perform certain routines repeatedly to the extent where it induces distress or impairs general ...
are also diagnosed with DSPD at a much higher rate than the general public.


Head injury

There have been several documented cases of DSPD and
non-24-hour sleep–wake disorder Non-24-hour sleep–wake disorder (non-24 or N24SWD) is one of several chronic circadian rhythm sleep disorders (CRSDs). It is defined as a "chronic steady pattern comprising ..daily delays in sleep onset and wake times in an individual living ...
developing after traumatic
head injury A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of inju ...
. There have been cases of DSPD developing into non-24-hour sleep–wake disorder, a severe and debilitating disorder in which the individual sleeps later each day.


Mechanism

DSPD is a disorder of the body's timing system—the biological clock. Individuals with DSPD might have an unusually long circadian cycle, might have a reduced response to the resetting effect of daylight on the body clock, and/or may respond overly to the delaying effects of evening light and too little to the advancing effect of light earlier in the day. In support of the increased sensitivity to evening light hypothesis, "the percentage of melatonin suppression by a bright light stimulus of 1,000 lux administered 2 hours prior to the melatonin peak has been reported to be greater in 15 DSPD patients than in 15 controls." The altered phase relationship between the timing of sleep and the circadian rhythm of body core temperature has been reported previously in DSPD patients studied in entrained conditions. That such an alteration has also been observed in temporal isolation (i.e; in absence of all external time cues) supports the notion that the etiology of DSPD goes beyond simply a reduced capacity to achieve and maintain the appropriate phase relationship between sleep timing and the 24-hour day. Rather, the disorder may also reflect a fundamental inability of the endogenous circadian timing system to maintain normal ''internal'' phase relationships among physiological systems, and to properly adjust those internal relationships within the confines of the 24-hour day. In normal subjects, the phase relationship between sleep and temperature changes in temporal isolation relative to that observed under entrained conditions: in isolation, temperature minimum tends to occur toward the beginning of sleep, whereas under entrained conditions, temperature minimum occurs toward the end of the sleep period—a change in phase angle of several hours; DSPD patients may have a reduced capacity to achieve such a change in phase angle in response to
entrainment Entrainment may refer to: * Air entrainment, the intentional creation of tiny air bubbles in concrete * Brainwave entrainment, the practice of entraining one's brainwaves to a desired frequency * Entrainment (biomusicology), the synchronization o ...
. Possibly as a consequence of these altered internal phase relationships, that the quality of sleep in DSPD may be substantially poorer than that of normal subjects, even when bedtimes and wake times are self-selected. A DSPD subject exhibited an average sleep onset latency twice that of the 3 control subjects and almost twice the amount of wakefulness after sleep onset (WASO) as control subjects, resulting in significantly poorer sleep efficiency. Also, the temporal distribution of slow wave sleep was significantly altered in the DSPD subject. This finding may suggest that, in addition to abnormal circadian clock function, DSPD may be characterized by alteration(s) in the homeostatic regulation of sleep, as well. Specifically, the rate with which Process S is depleted during sleep may be slowed. This could, conceivably, contribute to the excessive
sleep inertia Sleep inertia is a physiological state of impaired cognitive and sensory-motor performance that is present immediately after awakening. It persists during the transition of sleep to wakefulness, where an individual will experience feelings of drows ...
upon awakening that is often reported by those with DSPD. It has also been hypothesized that, due to the altered phase angle between sleep and temperature observed in DSPD, and the tendency for longer sleep periods, these individuals may simply sleep through the phase-advance portion of the light PRC. Though quite limited in terms of the total number of DSPD patients studied, such data seem to contradict the notion that DSPD is merely a disorder of sleep ''timing'', rather than a disorder of the sleep system itself. People with normal circadian systems can generally fall asleep quickly at night if they slept too little the night before. Falling asleep earlier will in turn automatically help to advance their circadian clocks due to decreased light exposure in the evening. In contrast, people with DSPD have difficulty falling asleep before their usual sleep time, even if they are sleep-deprived. Sleep deprivation does not reset the circadian clock of DSPD patients, as it does with normal people. People with the disorder who try to live on a normal schedule cannot fall asleep at a "reasonable" hour and have extreme difficulty waking because their biological clocks are not in phase with that schedule. ''Non''-DSPD people who do not adjust well to working a night shift have similar symptoms (diagnosed as shift-work sleep disorder).


Genetic factors

Researchers in 2017 linked DSPD to at least one genetic mutation. The syndrome usually develops in early childhood or
adolescence Adolescence () is a transitional stage of physical and psychological development that generally occurs during the period from puberty to adulthood (typically corresponding to the age of majority). Adolescence is usually associated with the t ...
. An adolescent version may disappear in late adolescence or early adulthood; otherwise, DSPD is a lifelong condition. The best estimate of prevalence among adults is 0.13–0.17% (1 in 600). Prevalence among adolescents is as much as 7–16%. In most cases, it is not known what causes the abnormality in the biological clocks of DSPD patients. DSPD tends to run in families, and a growing body of evidence suggests that the problem is associated with the hPer3 (human period 3) gene and CRY1 gene. For people who may have a circadian period significantly longer than 24 hours, a
differential diagnosis In healthcare, a differential diagnosis (abbreviated DDx) is a method of analysis of a patient's history and physical examination to arrive at the correct diagnosis. It involves distinguishing a particular disease or condition from others that p ...
may be warranted.


Diagnosis

DSPD is diagnosed by a clinical interview, actigraphic monitoring, and/or a
sleep diary A sleep diary is a record of an individual's sleeping and waking times with related information, usually over a period of several weeks. It is self-reported or can be recorded by a care-giver. The sleep diary, or sleep log, is a tool used by docto ...
kept by the patient for at least two weeks. When
polysomnography Polysomnography (PSG), a type of sleep study, is a multi-parameter study of sleep and a diagnostic tool in sleep medicine. The test result is called a polysomnogram, also abbreviated PSG. The name is derived from Greek and Latin roots: the Gree ...
is also used, it is primarily for the purpose of ruling out other disorders such as
narcolepsy Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep–wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affec ...
or
sleep apnea Sleep apnea, also spelled sleep apnoea, is a sleep disorder in which pauses in breathing or periods of shallow breathing during sleep occur more often than normal. Each pause can last for a few seconds to a few minutes and they happen many tim ...
. DSPD is frequently misdiagnosed or dismissed. It has been named as one of the sleep disorders most commonly misdiagnosed as a primary
psychiatric disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitt ...
.
See also subsequent:
*
DSPD is often confused with psychophysiological insomnia; depression; psychiatric disorders such as
schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social withdra ...
, ADHD or ADD; other sleep disorders; or
school refusal School refusal is a child-motivated refusal to attend school or difficulty remaining in class for the full day. Child-motivated absenteeism occurs autonomously, by the volition of the child. This behavior is differentiated from non-child-motivated ...
. Practitioners of
sleep medicine Sleep medicine is a medical specialty or subspecialty devoted to the diagnosis and therapy of sleep disturbances and sleep disorder, disorders. From the middle of the 20th century, research has provided increasing knowledge and answered many ...
point out the dismally low rate of accurate diagnosis of the disorder, and have often asked for better physician education on sleep disorders.


Definition

According to the
International Classification of Sleep Disorders The International Classification of Sleep Disorders (ICSD) is "a primary diagnostic, epidemiological and coding resource for clinicians and researchers in the field of sleep and sleep medicine". The ICSD was produced by the American Academy of Sle ...
, Revised (ICSD-R, 2001), the circadian rhythm sleep disorders share a common underlying chronophysiologic basis: Incorporating minor updates (ICSD-3, 2014), the diagnostic criteria for delayed sleep phase disorder are: Some people with the condition adapt their lives to the delayed sleep phase, avoiding morning business hours as much as possible. The ICSD's severity criteria are: * Mild: Two-hour delay (relative to the desired sleep time) associated with little or mild impairment of social or occupational functioning. * Moderate: Three-hour delay associated with moderate impairment. * Severe: Four-hour delay associated with severe impairment. Some features of DSPD which distinguish it from other sleep disorders are: * People with DSPD have at least a normal—and often much greater than normal—ability to sleep during the morning, and sometimes in the afternoon as well. In contrast, those with chronic insomnia do not find it much easier to sleep during the morning than at night. * People with DSPD fall asleep at more or less the same time every night, and sleep comes quite rapidly if the person goes to bed near the time they usually fall asleep. Young children with DSPD resist going to bed before they are sleepy, but the bedtime struggles disappear if they are allowed to stay up until the time they usually fall asleep. * DSPD patients usually sleep well and regularly when they can follow their own sleep schedule, e.g., on weekends and during vacations. * DSPD is a chronic condition. Symptoms must have been present for at least three months before a diagnosis of DSPD can be made. Often people with DSPD manage only a few hours sleep per night during the working week, then compensate by sleeping until the afternoon on weekends. Sleeping late on weekends, and/or taking long naps during the day, may give people with DSPD relief from daytime sleepiness but may also perpetuate the late sleep phase. People with DSPD can be called " night owls". They feel most alert and say they function best and are most creative in the evening and at night. People with DSPD cannot simply force themselves to sleep early. They may toss and turn for hours in bed, and sometimes not sleep at all, before reporting to work or school. Less-extreme and more-flexible night owls are within the normal
chronotype A chronotype is the behavioral manifestation of underlying circadian rhythm's myriad of physical processes. A person's chronotype is the propensity for the individual to sleep at a particular time during a 24-hour period. ''Eveningness'' (delayed ...
spectrum. By the time those who have DSPD seek medical help, they usually have tried many times to change their sleeping schedule. Failed tactics to sleep at earlier times may include maintaining proper
sleep hygiene Sleep hygiene is a behavioral and environmental practice developed in the late 1970s as a method to help people with mild to moderate insomnia. Clinicians assess the sleep hygiene of people with insomnia and other conditions, such as depression, ...
,
relaxation technique A relaxation technique (also known as relaxation training) is any method, process, procedure, or activity that helps a person to relax; to attain a state of increased calmness; or otherwise reduce levels of pain, anxiety, stress or anger. Relaxa ...
s, early bedtimes,
hypnosis Hypnosis is a human condition involving focused attention (the selective attention/selective inattention hypothesis, SASI), reduced peripheral awareness, and an enhanced capacity to respond to suggestion.In 2015, the American Psychologica ...
,
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
, sleeping pills, dull reading, and
home remedies Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...
. DSPD patients who have tried using
sedatives A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but th ...
at night often report that the medication makes them feel tired or relaxed, but that it fails to induce sleep. They often have asked family members to help wake them in the morning, or they have used multiple
alarm clock An alarm clock (or sometimes just an alarm) is a clock that is designed to alert an individual or group of individuals at a specified time. The primary function of these clocks is to awaken people from their night's sleep or short naps; they ar ...
s. As the disorder occurs in childhood and is most common in adolescence, it is often the patient's parents who initiate seeking help, after great difficulty waking their child in time for school. The current formal name established in the third edition of the International Classification of Sleep Disorders (ICSD-3) is delayed sleep-wake phase disorder. Earlier, and still common, names include delayed sleep phase disorder (DSPD), delayed sleep phase syndrome (DSPS), and circadian rhythm sleep disorder, delayed sleep phase type (DSPT).


Management

Treatment, a set of management techniques, is specific to DSPD. It is different from treatment of insomnia, and recognizes the patients' ability to sleep well on their own schedules, while addressing the timing problem. Success, if any, may be partial; for example, a patient who normally awakens at noon may only attain a wake time of 10 or 10:30 with treatment and follow-up. Being consistent with the treatment is paramount. Before starting DSPD treatment, patients are often asked to spend at least a week sleeping regularly, without napping, at the times when the patient is most comfortable. It is important for patients to start treatment well-rested.


Non-pharmacological

One treatment strategy is
light therapy Light therapy, also called phototherapy or bright light therapy is intentional daily exposure to direct sunlight or similar-intensity artificial light in order to treat medical disorders, especially seasonal affective disorder (SAD) and circad ...
(phototherapy), with either a bright white lamp providing 10,000 lux at a specified distance from the eyes or a wearable LED device providing 350–550 lux at a shorter distance. Sunlight can also be used. The light is typically timed for 30–90 minutes at the patient's usual time of spontaneous awakening, or shortly before (but not long before), which is in accordance with the
phase response curve A phase response curve (PRC) illustrates the transient change (phase response) in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received. PRCs are used in various fields; examples of biolog ...
(PRC) for light. Only experimentation, preferably with specialist help, will show how great an advance is possible and comfortable. For maintenance, some patients must continue the treatment indefinitely; some may reduce the daily treatment to 15 minutes; others may use the lamp, for example, just a few days a week or just every third week. Whether the treatment is successful is highly individual. Light therapy generally requires adding some extra time to the patient's morning routine. Patients with a family history of
macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, som ...
are advised to consult with an eye doctor. The use of exogenous melatonin administration (see below) in conjunction with light therapy is common. Light restriction in the evening, sometimes called darkness therapy or scototherapy, is another treatment strategy. Just as bright light upon awakening should advance one's sleep phase, bright light in the evening and night delays it (see the PRC). It is suspected that DSPD patients may be overly sensitive to evening light. The photopigment of the retinal
photosensitive ganglion cell Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye. The presence ...
s,
melanopsin Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene ''Opn4''. In the mammalian retina, there are two additional categories of opsins, both involved in the for ...
, is excited by light mainly in the blue portion of the visible spectrum (absorption peaks at ~480 nanometers). A formerly popular treatment, phase delay chronotherapy, is intended to reset the circadian clock by manipulating bedtimes. It consists of going to bed two or more hours later each day for several days until the desired bedtime is reached, and it often must be repeated every few weeks or months to maintain results. Its safety is uncertain, notably because it has led to the development of non-24-hour sleep-wake rhythm disorder, a much more severe disorder. A modified chronotherapy is called controlled sleep deprivation with phase advance, SDPA. One stays awake one whole night and day, then goes to bed 90 minutes ''earlier'' than usual and maintains the new bedtime for a week. This process is repeated weekly until the desired bedtime is reached. Earlier exercise and meal times can also help promote earlier sleep times.


Pharmacological

Aripiprazole Aripiprazole, sold under the brand names Abilify and Aristada among others, is an atypical antipsychotic. It is primarily used in the treatment of schizophrenia and bipolar disorder. Other uses include as an add-on treatment in major depressiv ...
(brand name Abilify) is an atypical antipsychotic that has been shown to be effective in treating DSPD by advancing sleep onset, sleep midpoint, and sleep offset at relatively low doses.
Melatonin Melatonin is a natural product found in plants and animals. It is primarily known in animals as a hormone released by the pineal gland in the brain at night, and has long been associated with control of the sleep–wake cycle. In vertebrates ...
taken an hour or so before the usual bedtime may induce sleepiness. Taken this late, it does not, of itself, affect circadian rhythms, but a decrease in exposure to light in the evening is helpful in establishing an earlier pattern. In accordance with its phase response curve (PRC), a very small dose of melatonin can also, or instead, be taken some hours earlier as an aid to resetting the body clock; it must then be small enough not to induce excessive sleepiness. Side effects of melatonin may include sleep disturbance,
nightmares A nightmare, also known as a bad dream, Retrieved 11 July 2016. is an unpleasant dream that can cause a strong emotional response from the mind, typically fear but also despair, anxiety or great sadness. The dream may contain situations of d ...
, daytime sleepiness, and depression, though the current tendency to use lower doses has decreased such complaints. Large doses of melatonin can even be counterproductive: Lewy et al. provide support to "the idea that too much melatonin may spill over onto the wrong zone of the melatonin phase-response curve." The long-term effects of melatonin administration have not been examined. In some countries, the hormone is available only by prescription or not at all. In the United States and Canada, melatonin is on the shelf of most pharmacies and herbal stores. The prescription medication
ramelteon Ramelteon, sold under the brand name Rozerem among others, is a melatonin agonist medication which is used in the treatment of insomnia. It is indicated specifically for the treatment of insomnia characterized by difficulties with sleep onset. ...
(Rozerem) is a melatonin analogue that selectively binds to the melatonin MT1 and MT2 receptors and, hence, has the possibility of being effective in the treatment of DSPD. A review by the
US Department of Health and Human Services The United States Department of Health and Human Services (HHS) is a cabinet-level executive branch department of the U.S. federal government created to protect the health of all Americans and providing essential human services. Its motto is ...
found little difference between melatonin and placebo for most primary and secondary sleep disorders. The one exception, where melatonin is effective, is the "circadian abnormality" DSPD. Another systematic review found inconsistent evidence for the efficacy of melatonin in treating DSPD in adults, and noted that it was difficult to draw conclusions about its efficacy because many recent studies on the subject were uncontrolled.
Modafinil Modafinil, sold under the brand name Provigil among others, is a central nervous system (CNS) stimulant medication used to treat sleepiness due to narcolepsy, shift work sleep disorder, and obstructive sleep apnea. While it has seen off-label ...
(brand name Provigil) is a stimulant approved in the US for treatment of shift-work sleep disorder, which shares some characteristics with DSPD. A number of clinicians prescribe it for DSPD patients, as it may improve a sleep-deprived patient's ability to function adequately during socially desirable hours. It is generally not recommended to take modafinil after noon; modafinil is a relatively long-acting drug with a half-life of 15 hours, and taking it during the later part of the day can make it harder to fall asleep at bedtime. Vitamin B12 was, in the 1990s, suggested as a remedy for DSPD, and is still recommended by some sources. Several case reports were published. However, a review for the American Academy of Sleep Medicine in 2007 concluded that no benefit was seen from this treatment.


Prognosis


Risk of relapse

A strict schedule and good
sleep hygiene Sleep hygiene is a behavioral and environmental practice developed in the late 1970s as a method to help people with mild to moderate insomnia. Clinicians assess the sleep hygiene of people with insomnia and other conditions, such as depression, ...
are essential in maintaining any good effects of treatment. With treatment, some people with mild DSPD may sleep and function well with an earlier sleep schedule.
Caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...
and other stimulant drugs to keep a person awake during the day may not be necessary and should be avoided in the afternoon and evening, in accordance with good sleep hygiene. A chief difficulty of treating DSPD is in ''maintaining'' an earlier schedule after it has been established. Inevitable events of normal life, such as staying up late for a celebration or deadline, or having to stay in bed with an illness, tend to reset the sleeping schedule to its intrinsic late times. Long-term success rates of treatment have seldom been evaluated. However, experienced clinicians acknowledge that DSPD is extremely difficult to treat. One study of 61 DSPD patients, with average sleep onset at about 3:00 am and average waking time of about 11:30 am, was followed with questionnaires to the subjects after a year. Good effect was seen ''during'' the six-week treatment with a large daily dose of melatonin. After ceasing melatonin use over 90% had relapsed to pre-treatment sleeping patterns within the year, 29% reporting that the relapse occurred within one week. The mild cases retained changes significantly longer than the severe cases.


Adaptation to late sleeping times

Working the evening or night shift, or working at home, makes DSPD less of an obstacle for some. Many of these people do not describe their pattern as a "disorder". Some DSPD individuals nap, even taking 4–5 hours of sleep in the morning and 4–5 in the evening. DSPD-friendly careers can include security work, the entertainment industry, hospitality work in restaurants, theaters, hotels or bars, call center work, manufacturing, healthcare or emergency medicine,
commercial cleaning Commercial cleaning companies are contracted to carry out cleaning jobs in a variety of premises. Cleaning techniques and equipment Commercial office cleaning companies use a wide variety of cleaning methods, chemicals, and equipment to facil ...
, taxi or truck driving, the media, and freelance writing, translation, IT work, or
medical transcription Medical transcription, also known as MT, is an allied health profession dealing with the process of transcribing voice-recorded medical reports that are dictated by physicians, nurses and other healthcare practitioners. Medical reports can be vo ...
. Some other careers that have an emphasis on early morning work hours, such as bakers, coffee baristas, pilots and flight crews, teachers, mail carriers, waste collection, and farming, can be particularly difficult for people who naturally sleep later than is typical. Some careers, such as over-the-road truck drivers, firefighters, law enforcement, nursing, can be suitable for both people with delayed sleep phase syndrome and people with the opposite condition,
advanced sleep phase disorder Advanced Sleep Phase Disorder (ASPD), also known as the advanced sleep-phase type (ASPT) of circadian rhythm sleep disorder, is a condition that is characterized by a recurrent pattern of early evening (e.g. 7-9 PM) sleepiness and very early morn ...
, as these workers are needed both very early in the morning and also late at night. Some people with the disorder are unable to adapt to earlier sleeping times, even after many years of treatment. Sleep researchers Dagan and Abadi have proposed that the existence of untreatable cases of DSPD be formally recognized as a "sleep-wake schedule disorder (SWSD) disability", an
invisible disability Invisible disabilities, also known as hidden disabilities or non-visible disabilities (NVD), are disabilities that are not immediately apparent, are typically chronic illnesses and conditions that significantly impair normal activities of dail ...
.
Rehabilitation Rehabilitation or Rehab may refer to: Health * Rehabilitation (neuropsychology), therapy to regain or improve neurocognitive function that has been lost or diminished * Rehabilitation (wildlife), treatment of injured wildlife so they can be retur ...
for DSPD patients includes
acceptance Acceptance in human psychology is a person's assent to the reality of a situation, recognizing a process or condition (often a negative or uncomfortable situation) without attempting to change it or protest it. The concept is close in meaning to ...
of the condition and choosing a career that allows late sleeping times or running a home business with flexible hours. In a few schools and universities, students with DSPD have been able to arrange to take exams at times of day when their concentration levels may be good. In the United States, the
Americans with Disabilities Act The Americans with Disabilities Act of 1990 or ADA () is a civil rights law that prohibits discrimination based on disability. It affords similar protections against discrimination to Americans with disabilities as the Civil Rights Act of 1964 ...
requires that employers make
reasonable accommodation A reasonable accommodation is an adjustment made in a system to accommodate or make fair the same system for an individual based on a proven need. That need can vary. Accommodations can be religious, physical, mental or emotional, academic, physic ...
s for employees with sleeping disorders. In the case of DSPD, this may require that the employer accommodate later working hours for jobs normally performed on a "9 to 5" work schedule. The statute defines "disability" as a "physical or mental impairment that substantially limits one or more major life activities", and Section 12102(2)(a) itemizes sleeping as a "major life activity".


Impact on patients

Lack of public awareness of the disorder contributes to the difficulties experienced by people with DSPD, who are commonly stereotyped as undisciplined or lazy. Parents may be chastised for not giving their children acceptable sleep patterns, and schools and workplaces rarely tolerate chronically late, absent, or sleepy students and workers, failing to see them as having a chronic condition. As DSPD is so little-known and so misunderstood,
peer support Peer support occurs when people provide knowledge, experience, emotional, social or practical help to each other. It commonly refers to an initiative consisting of trained supporters (although it can be provided by peers without training), and can ...
may be important for information, self-acceptance, and future research studies. People with DSPD who force themselves to follow a normal 9–5 workday "are not often successful and may develop physical and psychological complaints during waking hours, e.g., sleepiness, fatigue, headache, decreased appetite, or depressed mood. Patients with circadian rhythm sleep disorders often have difficulty maintaining ordinary social lives, and some of them lose their jobs or fail to attend school."


Epidemiology

There have been several studies that have attempted to estimate the prevalence of DSPD. Results vary due to differences in methods of data collection and diagnostic criteria. A particular issue is where to draw the line between extreme evening chronotypes and clinical DSPD. Using the ICSD-1 diagnostic criteria (current edition ICSD-3) a study by telephone questionnaire in 1993 of 7,700 randomly selected adults (aged 18–67) in Norway estimated the prevalence of DSPD at 0.17%. A similar study in 1999 of 1,525 adults (aged 15–59) in Japan estimated its prevalence at 0.13%. A somewhat higher prevalence of 0.7% was found in a 1995 San Diego study. A 2014 study of 9100 New Zealand adults (age 20–59) using a modified version of the
Munich Chronotype Questionnaire The Munich Chronotype Questionnaire (MCTQ) was created in 1976 by Till Roenneberg and Martha Merrow at Ludwig-Maximilians University The Ludwig Maximilian University of Munich (simply University of Munich or LMU; german: Ludwig-Maximilians-Uni ...
found a DSPD prevalence of 1.5% to 8.9% depending on the strictness of the definition used. A 2002 study of older adults (age 40–65) in San Diego found 3.1% had complaints of difficulty falling asleep at night and waking in the morning, but did not apply formal diagnostic criteria. Actimetry readings showed only a small proportion of this sample had delays of sleep timing. A marked delay of sleep patterns is a normal feature of the development of adolescent humans. According to
Mary Carskadon Mary A. Carskadon is one of the most prominent American researchers in sleep. She is a Professor in the Department of Psychiatry and Human Behavior at the Warren Alpert Medical School of Brown University. She is also the Director of the Sleep and ...
, both circadian phase and
homeostasis In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
(the accumulation of sleep pressure during the wake period) contribute to a DSPD-like condition in post-pubertal as compared to pre-pubertal youngsters. Adolescent sleep phase delay "is present both across cultures and across mammalian species" and "it seems to be related to pubertal stage rather than age." As a result, diagnosable DSPD is much more prevalent among adolescents. with estimates ranging from 3.4% to 8.4% among high school students.


See also

*
Chronobiology Chronobiology is a field of biology that examines timing processes, including periodic (cyclic) phenomena in living organisms, such as their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobi ...
* Cultural jet lag *
Irregular sleep–wake rhythm Irregular sleep–wake rhythm (ISWD) is a rare form of circadian rhythm sleep disorder. It is characterized by numerous naps throughout the 24-hour period, no main nighttime sleep episode, and irregularity from day to day. Affected individuals ha ...
*
Morningness–eveningness questionnaire The morningness–eveningness questionnaire (MEQ) is a self-assessment questionnaire developed by researchers James A. Horne and Olov Östberg in 1976. Its main purpose is to measure whether a person's circadian rhythm (biological clock) produce ...
*
Non-24-hour sleep–wake disorder Non-24-hour sleep–wake disorder (non-24 or N24SWD) is one of several chronic circadian rhythm sleep disorders (CRSDs). It is defined as a "chronic steady pattern comprising ..daily delays in sleep onset and wake times in an individual livin ...
*
Seasonal affective disorder Seasonal affective disorder (SAD) is a mood disorder subset, in which people who have normal mental health throughout most of the year exhibit depressive symptoms at the same time each year. Common symptoms include sleeping too much, having li ...
(SAD) *
Sleep inertia Sleep inertia is a physiological state of impaired cognitive and sensory-motor performance that is present immediately after awakening. It persists during the transition of sleep to wakefulness, where an individual will experience feelings of drows ...


References


External links

{{Sleep Sleep disorders Circadian rhythm Syndromes Sleep physiology