Circadian Rhythm Sleep Disorders.

Circadian rhythm disorders involve abnormalities in the circadian time-keeping system, caused by alterations in  the day-night sleep cycle, they consist of two major categories, transient and persistent.

The transient disorder may follow an abrupt change in the sleep wake cycle due to shift work, which requires a person to change from activity during the day and sleeping at night , to activity at night and sleeping during the day. Many workers experience difficulty adjusting to the change, and until they manage to make the adjustment to the new 24 hour sleep-wake cycle, their circadian rhythms remain desychronized, unfortunately shift work makes demands on workers  performance capabilities, when they are at their lowest. Circadian rhythms suffer desynchronization when people cross multiple time zones, this is referred to as jet lag.

The major consequences of disruption to the normal circadian rhythms by shift work include, alterations in the quality and quantity of sleep, persistent fatigue, behavioral changes, and inability to concentrate. Sleep is often reduced by as much as four hours, resulting in loss of REM and stage 2 sleep.

The changing sleep-wake patterns, coupled with conflicting environmental time cues, exacerbate the effects of sleep deficit, resulting in poor performance, reduced sense of well-being, and an increased risk of coronary artery disease, and peptic ulcer. It has been reported that older shift workers are far more likely to be affected by alteration to their circadian rhythms, than younger people, and may prove unable to make the adjustment.

The absence of external time cues has also proven to exert a strong influence on circadian rhythms, for research has proven that circadian rhythms are not only modified endogenously, but also respond to external environmental cues such as, light dark alterations, atmospheric changes, and other environmental cues. Patients in intensive care units risk suffering desynchronization of their circadian rhythms through being placed in an environment of almost constant lighting, activity, noise, and medication. The illness they may be suffering from, particularly if it is severe, will also play a part in contributing to circadian rhythm sleep disorder.

Delayed sleep phase syndrome is a circadian rhythm disorder in which the individual experiences difficulty initiating sleep at a socially accepted time and may not be able to sleep until the early hours of the morning. Consequently waking for the normal demands of work and family life poses huge problems for these people. An interesting aspect of this delayed sleep phase syndrome is that when a time schedule  is removed, such as on weekends and vacations they do not experience the DPS syndrome. From this it would appear that these people have an entirely different problem than DPS syndrome, and may need to change jobs, school, or adjust their attitude to social demands. Giving a title to their behavior problem only maintains and excuses their behavior , rather than curing it, listing it as a circadian rhythm sleep disorder is misleading.

Read more:Shift Work and Pathological Conditions