Circadian rhythm sleep disorder

Circadian rhythm sleep disorder is a disruption of the regularity of the sleep-wake cycle due to desynchronization of the external and internal clocks. There are disturbances in night sleep, abnormal daytime sleepiness, or a combination of both, which usually pass, since the biological clock itself is rebuilt. The diagnosis is clinical. Treatment is aimed at eliminating the cause of the failure.

Circadian rhythm sleep disorder can be caused by external stimuli and causes (e.g., jet lag when moving to another time zone, shift work) or due to desynchronization of the internal biological clock with the day/night cycle (e.g., late or early bedtime syndrome).

The most common oral sleeping pills

Preparation	Half-life, h	Dose, mg2	Comments
Benzodiazepines
Flurazepam	40-250	15-30	High risk of residual sedation next day; not recommended for elderly
Quazepam	40-250	7.5-15	It has high lipophilicity, which can soften residual sedation in the first 7-10 days with long-term use.
Estazolam	10-24	0.5-2	Effective for induction and maintenance
Temazepam	8-22	7.5-15	The drug has the longest period of sleep induction
Triazolam	<6	0.125-0.5	May cause anterograde amnesia; high risk of developing tolerance and addiction
Imidazopyridine
Zolpidem	2.5	5-10	Effective for induction and maintenance
Pyrazolopyrimadine
Zaleplon	1	5-20	Ultra-short-acting drug; improves sleep onset at the onset of sleep or after nighttime awakening (for at least 4 hours); taking before bedtime minimizes residual effects

¹ Including precursors and active metabolites. ² Doses are given at bedtime.

Sleep desynchronization due to external causes also disrupts other circadian rhythms of the body, including hormonal secretion and temperature. In addition to insomnia and drowsiness, these changes may be accompanied by nausea, malaise, irritability, and depression. The most unfavorable are repeated disruptions of the circadian rhythm (e.g., frequent long-distance travel, rotation of work shifts). It takes a long time to restore circadian rhythms and eliminate sleep disturbances. Since light is the most powerful determinant of normalization of the circadian rhythm, exposure to bright light (sunlight or artificial light with an intensity of 5,000-10,000 lux) after awakening helps speed up adaptation to new conditions. Melatonin can also be used (see above).

Using alcohol, sleeping pills, and stimulants to correct circadian rhythm disorders is not a good strategy.

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Jet lag syndrome (a disruption of the biorhythm when moving to another time zone)

This syndrome is caused by rapid travel across two or more time zones. Traveling east (shifting sleep to an earlier time) causes a more pronounced disruption than traveling west (shifting sleep to a later time).

If possible, before a long trip, it is recommended to gradually shift your sleep-wake cycle to match the conditions of your intended destination and to maximize your exposure to daylight (especially in the morning) in your new destination. In addition, short-acting sleep aids or stimulants (such as modafinil) may be used for a short period after arrival.

Sleep disturbances in shift work

The severity of symptoms is proportional to the frequency of shift rotations, the length of each shift, and the frequency of "counterclockwise" shift shifts (advancing sleep times). Fixed shift work (i.e., night or evening work) is preferred; shift rotation should be "clockwise" (i.e., day-evening-night). However, even with fixed shift work, impairments are noted because daytime noise and light impair sleep quality, and workers often shorten their sleep time to participate in social or family activities.

In shift work, maximum exposure to bright light (sunlight or, for those working at night, artificial light) during the waking period is recommended, as well as the creation of the most comfortable conditions for sleep (a dark and quiet bedroom). Darkening eye masks and noise-cancelling devices can be used. In cases of persistent sleep disorders that negatively affect daily activities, the judicious use of short-acting sleeping pills and stimulants is indicated.

Sleep phase disorder syndromes

In these syndromes, the normal quality and total duration of sleep in a 24-hour circadian rhythm cycle are preserved, but the distribution of sleep time during the day is disrupted, i.e. there are shifts in the time of falling asleep and waking up. In rarer cases, the cycle does not fit into 24 hours, i.e. patients wake up from day to day at different times, sometimes earlier, sometimes later, but if it is possible to adhere to their natural cycle, sleep disorders do not develop.

Late sleep onset syndrome (delayed sleep phase syndrome) is characterized by late sleep onset and late awakening (e.g., 3:00 AM and 10:00 AM) due to a sleep disorder in which the patient's sleep time is approximately 3 hours after the time he or she would like to fall asleep. This syndrome is more common in adolescence. The need to get up early to go to work or school is associated with increased daytime sleepiness, poor school performance, and missed morning classes. They can be distinguished from people who go to bed late because they cannot fall asleep earlier, even if they try. Mild delays in sleep time (less than 3 hours) are treated with gradual earlier awakening and bright daylight therapy. Melatonin can be taken before bedtime.

Early sleep onset syndrome (early falling asleep and waking up early) is more common among older people. Bright light therapy in the evening can be used to correct it.