In patients with CRSDs, sleep episodes occur at inappropriate times, often caus-ing waking periods to occur at undeslred times. Consequently, the patient complains of insomnia or excessive daytime sleepiness and impairment in various areas of functioning. The second edition of the international Classification of Sleep Disorders (ICSD-2)1 divides disorders of sleep-wake schedule into three major categories: CRSDs of primary

origin, behavlorally induced CRSDs, Inhibitors,research,lifescience,medical and CRSDs due to a substance. Behavlorally induced CRSDs can emerge as a consequence of the individual’s voluntary choice to create a temporal mismatch between his or her sleep-wake cycle and environmental conditions, as happens Inhibitors,research,lifescience,medical in shift work and jet lag. This review will focus on primary CRSDs and behavioral and psychiatric consequences of these disorders. Alterations of the sleep-wake schedule following treatment with psychoactive medications will also be described in some detail. Four types of primary CRSD are listed in the ICSD-2: Delayed sleep phase type, also known as delayed sleep phase syndrome (DSPS), which is characterized by habitual sleep-wake times that are delayed usually more than 2 h relative to conventional or socially

acceptable times Inhibitors,research,lifescience,medical (Figure 1A). When forced to follow an environmentally imposed schedule, these patients will complain of difficulties falling asleep and waking up in the morning, and feel sleepy during the day. Figure 1. Actigrams of patients Inhibitors,research,lifescience,medical with disorderd sleep-wake schedules. Sleep episodes are represented by white areas, wake episodes by black areas. The 24-h period is double-plotted in

a Ion Channel Ligand Library in vivo raster format. A. Delayed sleep phase syndrome. B. Advanced sleep phase syndrome. … Advanced sleep phase type, also known as advanced sleep phase syndrome (ASPS), which is characterized by habitual sleep onset and wake-up times that are several hours earlier than desired or socially accepted (Figure 1B), This pattern results in symptoms of compelling evening sleepiness, early sleep onset, Inhibitors,research,lifescience,medical and awakening that is earlier than desired. Free-running type, also known as nonentrained type or non-24-h sleep-wake syndrome, can be described by a sleep-wake cycle that is usually longer than the 24-h period. Sleep and wake episodes are delayed each day to later Isotretinoin hours, thus alternating between synchrony and complete asynchrony with the environmental schedule (Figure 1C). Irregular sleep-wake type, also known as irregular or disorganized sleep-wake pattern, is characterized by lack of clearly defined circadian sleep-wake rhythm. Sleep and wake episodes are temporally disorganized and variable throughout the 24-h period (Figure 1D). These patients are likely to manifest inability to initiate and maintain sleep at night, frequent daytime napping, and excessive daytime sleepiness.