A clinical approach to circadian rhythm sleep disorders

Abstract

Circadian rhythm sleep disorders are characterized by complaints of insomnia and excessive sleepiness that are primarily due to alterations in the internal circadian timing system or a misalignment between the timing of sleep and the 24-h social and physical environment. In addition to physiological and environmental factors, maladaptive behaviors often play an important role in the development of many of the circadian rhythm sleep disorders. This review will focus on the clinical approach to the diagnosis and management of the various circadian rhythm sleep disorders, including delayed sleep phase disorder, advanced sleep phase disorder, non-entrained type, irregular sleep-wake rhythm, shift work sleep disorder and jet lag disorder. Diagnostic tools such as sleep diaries and wrist activity monitoring are often useful in confirming the diagnosis. Because behavioral and environmental factors often are involved in the development of these conditions, a multimodal approach is usually necessary. Interventions include sleep hygiene education, timed exposure to bright light as well as avoidance of bright light at the wrong time of the day and pharmacologic approaches, such as melatonin. However, it should be noted that the use of melatonin is not an FDA-approved indication for the treatment of circadian rhythm sleep disorders.

Figure 1

An actogram of sleep-wake activity, recorded using wrist activity monitoring, from an individual with DSPD. This individual goes to bed around 5–6 a.m. and wakes between 12–1 p.m. each day. Note that all actigraphy data shown throughout this manuscript is double-plotted; i.e., a period of consecutive 48 hours is represented in each line and then the last 24 hours repeated on the following line.

Figure 2

As predicted by the human PRC (phase response curve) to light, bright light exposure in early mornings will advance the phase of circadian rhythms, while exposure to light in the evening will cause phase delays. As the melatonin PRC is approximately the inverse of PRC to light exposure, melatonin advances the phase rhythm when given in the early evening hours.

Figure 3

An actogram of sleep-wake activity, recorded using wrist activity monitoring, from an individual with ASPD. This individual goes to bed between 9–10 p.m. and wakes at 4 a.m. each day. There are two periods when the subject has taken off the wrist activity monitoring (Tuesday for about 2 hours and Thursday for about 3 hours).

Figure 4

An actogram of sleep-wake activity, recorded using activity monitoring from an individual with non-24-hour sleep-wake syndrome. Note the consistent delay in bedtime over the recording time.