Causes of Advanced or Delayed Sleep Phase Syndrome
Overall, four major areas play a role in ASPS and DSPS:
Genetics
Hormones
Physical Activity
Environmental triggers, such as the light of day
Although the exact cause of ASPS and DSPS is not known, it is known that the disorder is related to circadian rhythms, which regulate the internal biological clock and influence functions such as sleep-wake patterns.
In normal circumstances, circadian rhythms are in synch with the course and cycles of a 24-hour day/night environment. However, these rhythms can become abnormally disrupted, causing issues with a normal sleep/wake schedule. This can happen because of many factors, including:
Environmental disruptions: Excessive light, higher noise levels, and elevated room temperature are not conducive to good sleep and are important variables to consider.
Travel: The severity of jet lag is related to the direction of travel and is more frequently seen in individuals traveling in an eastward direction. The number of time zones crossed also has an effect on the severity of jet lag, with most individuals experiencing jet lag if they cross 3 or more time zones. The rate of adjustment is 1.5 hours per day after a westward flight and 1 hour per day after an eastward flight.
Sensitivity to light and other environmental cues: This sensitivity may be altered or disrupted, which can be demonstrated under certain conditions.
Neurological disease: Alzheimer's is one of the more common examples of neurological disease associated with a circadian rhythm disorder; however, irregular sleep/wake cycles can also be seen in other neurodegenerative diseases.
Shift work: Rapid shift changes and shift changes in the counterclockwise direction are most likely to cause symptoms of a circadian rhythm disorder.
