Four common sleep disorders and their features [26]
| Name | Features | Prevalence |
|---|---|---|
| ASPD/ASPS, ~2% | The sleep episode occurs in advance time than the desired clock time, leading to early sleep onset and early awakening than the desired time | ASPD is more prevalent in elderly people |
| This syndrome is rare and has a genetic basis. It is conferred by a single autosomal dominant gene that resides on the short arm of chromosome 2 which carries Per2 genes. Mutation results from serine-to-glycine in PER2 protein are the responsible party for this syndrome | ||
| Mutation in CK1ε lowers the rate of degradation of PER2 protein. Misregulation of PER2 protein promotes ASPS | ||
| DSPD/DSPS, 83% | The onset of sleep and final awakening are delayed concerning the desired clock time. The body temperature, melatonin, and sleep rhythm of DSPS subjects are very similar to normal subjects, but the phase is delayed. They are less productive in their profession and social life | DSPS may appear in early childhood but commonly occurs during adolescence and in middle age people. Social and occupational impairment can promote DSPS |
| FRD, ~2% | It is known as a non-24-h-sleep-wake syndrome and appears as a chronic disorder. In this pattern, progressive changes of 1-h to 2-h delays in sleep onset and wake times are the fundamental features | FRD is common in those who are blind and it may be due to failure of the entrainment to the LD cycle |
| The variable period length indicates the interaction between the environment and the sleep-wake cycle | ||
| ISWR, 12% | The pattern is temporally disorganized. The variable episodes of sleeping and waking behavior are very common. A short sleep period (a few hours) is distributed randomly throughout the day and night | ISWR is very common in night workers, shift workers, students of colleges, universities, technical institutes, medical schools, law schools, and research institutes |
| It has also been observed mainly in the mentally retarded and demented individuals |