Delayed sleep phase syndrome is a disorder of the circadian rhythm of sleep-wakefulness, in which the main problem is the delay in the time of the basic sleep episode in relation to the light-dark cycle. Clinically, there are problems falling asleep, the inability to wake up in the morning, the need to sleep in the afternoon, performance disorders. The diagnosis is established on the basis of anamnesis, complaints, results of polysomnography, actigraphy, electroencephalography. Melatonin treatment and psychotherapy are being carried out. It is recommended to reduce the effects of evening light, morning light therapy.
ICD 10
G47.2 Sleep and wake cycle disorders
General information
Delayed sleep phase syndrome is considered the most common variant of circadian insomnia. The true prevalence of pathology is difficult to assess, since people with moderate manifestations do not always seek medical help. According to the available literature, estimates of the prevalence of the syndrome obtained in various studies vary from 1% to 8.4%. Delayed sleep phase syndrome is considered to be the most common among adolescents and young adults. The age of patients often ranges from 16-26 years.
Causes
The etiofactors of the phase delay syndrome are not exactly known. Assume the leading role of individual genetically determined features of the body in the form of a biological rhythm duration of more than 24 hours or increased sensitivity to light. Among the alleged triggers of the delayed phase are:
- Mental disorders. Phase delay is observed in those suffering from depression, affective disorders, obsessive-compulsive disorders. However, it is not always clear whether the delayed onset of the falling asleep phase is secondary to the dysfunction of the mental sphere.
- Cystic fibrosis. A recent study revealed a significant delay in the sleep phase in patients with cystic fibrosis compared to the control group. The authors of the study suggested that the phase delay is the primary manifestation of dysfunction of the CFTR gene responsible for the development of cystic fibrosis in the central nervous system.
- Shift work. Working in the evening and at night for a long period leads to a persistent change in the circadian rhythm with a significant shift in falling asleep. A similar effect is provided by training in the late evenings.
- Behavioral factor. The habit of watching videos late at night, being active in the evening or doing sports, sleeping long in the morning contribute to the delay of the falling asleep phase. Frequent partying can also lead to the occurrence of the syndrome.
Pathogenesis
Light is the most important signal linking falling asleep and waking with the solar cycle through the short-wave blue component of the white light spectrum. The intensity of light is perceived by melanopsin contained in the photosensitive cells of the retina of the eye, and is transmitted to the suprachiasmatic nucleus through the retino-hypothalamic tract.
The pathogenesis of delayed sleep phase syndrome is presumably based on a scenario in which patients receive too much light in the evening due to excessive activity and too little in the period before noon due to the fact that they are sleeping. This generates a self-reproducing shift of the sleep-wake cycle. The start of melatonin production is delayed at dusk.
Among the mechanisms of the development of delayed sleep phase syndrome, an altered response to light stimuli is also assumed. The mechanism of changes in photosensitivity in adolescence and, in particular, during puberty, may be due to an increase in the level of sex hormones. In addition, the importance of evening artificial lighting in the phase delay mechanism should not be underestimated.
Symptoms
The main manifestation of the syndrome is a shift in the sleep phase. Patients note the inability to fall asleep earlier than 1-2 o’clock in the morning, great difficulties with waking up in the morning. Most of them get up at 10-11 o’clock in the morning. If an earlier rise is necessary, the duration of sleep is significantly reduced. However, this does not lead to earlier falling asleep.
Deprivation of night sleep during the working week is accompanied by a decrease in working capacity, a drowsy state during the daytime. When patients with delayed sleep syndrome can sleep according to a schedule that suits them, they have normal sleep quality and duration. At the same time, in most cases they demonstrate a stable 24-hour rhythm.
With the delay syndrome, not only the sleep phase is shifted, but also the period of peak activity. There is lethargy and passivity in the morning, animation and activity in the evening. On a day off, there is an increased need to sleep off, and therefore patients can sleep up to 12-13 hours.
Complications
The concomitant delay of the phase of chronic sleep restriction to 5-6 hours a day entails numerous detrimental consequences for physical and mental health. A person suffering from the syndrome experiences significant difficulties with getting up to work or school in the morning. In schoolchildren and students, this leads to frequent lateness, skipping classes, excessive drowsiness in class, poor academic performance.
In working patients, the delayed sleep phase syndrome is complicated by a decrease in efficiency, irritability, difficulties with concentration, which negatively affects professional activity. It is possible to develop increased anxiety, depression, and the use of psychoactive substances. A number of patients have insomnia.
Diagnostics
In modern somnology, the diagnosis of “delayed sleep phase syndrome” requires the presence of three criteria: characteristic sleep displacement, excessive drowsiness or insomnia, significant daytime disturbances in social, professional or other important spheres of life. After a thorough neurological examination with the exception of organic pathology according to the neurological status, the patient is referred to a somnologist.
For diagnostic purposes and to evaluate the effectiveness of therapy, patients are recommended to keep sleep diaries with recording the time of falling asleep and waking up. According to the indications, a psychiatric examination is carried out. Among the methods of instrumental diagnosis of the syndrome are used:
- Actigraphy. It is an addition to the observation diary. Allows you to objectively assess the time of onset and quality of the sleep phase with the help of long-term monitoring of motor activity.
- Polysomnography. It does not reveal specific disorders of the duration and structure of sleep if it occurs at a time comfortable for the patient. When conducting a study during the usual period for the average person (from 23 hours to 7 hours), a delay in the sleep phase, an increase in latency, and difficulty of awakening are revealed.
- Electroencephalography of sleep. In case of delay syndrome, it diagnoses a decrease in slow-wave activity compared to the normal chronotype. The absence of pathological changes in the encephalogram makes it possible to exclude the presence of organic pathology.
Differential diagnosis
Difdiagnosis is performed with other somnological disorders. A distinctive feature of the phase delay syndrome is a combination of falling asleep and waking disorders, their normalization if possible to sleep at the time chosen by the patient. It is also necessary to distinguish the syndrome from delayed sleep, due to increased evening activity and other habits.
Late falling asleep can be accompanied by psychopathies, phobias, panic attacks occurring at night. However, they are accompanied by corresponding psychological symptoms, and signs of autonomic dysfunction are revealed during panic attacks. Disorders of falling asleep with restless legs syndrome are combined with uncomfortable sensations in the lower extremities.
Sleep apnea syndrome is similar to delayed sleep phase syndrome by the presence of daytime sleepiness. However, it differs in normal immersion in sleep, the presence of night awakenings. The final diphdiagnosis is determined by the results of polysomnography, which does not reveal apnea.
Treatment
Therapy is aimed at gradually shifting falling asleep to the period before midnight. It boils down to regulating the level of lighting in the evening and morning, observing a certain regime with the exception of evening activity. The main principles of the treatment are:
- Melatonin therapy. Taking the drug is recommended in the evening, usually 3-4 hours before falling asleep. The doses of the drug are selected individually with a possible gradual increase in dosage until the desired effect is achieved. The most common complications include headache, nasopharyngitis. Melatonin should be used with caution in patients with hepatic insufficiency.
- Minimization of evening lighting. Numerous clinical studies have demonstrated significant effectiveness in minimizing exposure to evening (artificial) light. In addition to minimizing or dimming the lighting, it is recommended to use glasses with a blue light filter, glasses with yellow lenses. Patients should wear them after sunset.
- Morning light therapy. It involves the inclusion of natural sunlight or broad-spectrum white light (~1000 lux) from a specialized lamp at the usual wake-up time. The duration of light exposure is increased daily by 30 minutes. In the literature there are contradictory data on the effectiveness of the method. It can probably be considered as an addition to minimizing lighting in the evening.
- Cognitive behavioral psychotherapy. It is aimed at understanding the patient’s problem of falling asleep and its possible causes. During psychotherapeutic sessions, there is an awareness of the need for treatment, a change in behavioral habits. The patient has faith in the possibility of improvement against the background of ongoing therapy, which prevents the development of depression, improves socialization.
Prognosis and prevention
In most cases, when the patient is interested in the results of treatment, he fulfills all medical recommendations, it is possible to achieve a gradual shift of the phase of falling asleep to normal time. This leads to the restoration of the necessary duration of night sleep, the improvement of morning awakenings, the disappearance of daytime sleepiness.
If the delayed sleep phase syndrome occurs against the background of mental disorders, drug addiction, alcoholism, the prognosis is less favorable. Prevention of the syndrome consists in observing the daily routine. If there are problems with falling asleep in shift workers, a full transition to day shifts is necessary.