SOSWS

Sleep-onset SWS (SOSWS) is a short slow-wave-sleep latency, or an abnormally rapid transition from wakefulness to SWS, almost fully skipping the period of light sleep that normally characterizes the beginning of the sleep period.

Mechanism

After periods of sleep deprivation, and slow-wave-sleep deprivation in particular, a significant shortening of NREM3 and NREM4 latencies is usually expected.<1> Similarly to sleep onset REM<2>, SWS latency is <15 minutes in this case.

Application to polyphasic sleep

Generally polyphasic sleep schedules, which contain at least 3 full sleep cycles in core(-s), rarely cause significant SWS loss. SOSWS is more common for extreme schedules, such as the nap-only line. This mechanism causes entering SWS almost immediately, which allows to get SWS-filled naps.