AP PSYCHOLOGY

Detailed explanation-1: -A full sleep cycle takes about 90 to 110 minutes. Your first REM period is short. As the night goes on, you’ll have longer REM sleep and less deep sleep.

Detailed explanation-2: -Sleep research has shown that we go through the various light/deep/REM sleep states in a fairly consistent 90-minute cycle. This 90-minute pattern is closely linked to our circadian rhythms, our inbuilt body clock that naturally determines our wakefulness and sleepiness.

Detailed explanation-3: -The 90-minute snooze rule is based on timing the bedtime in a way that we wake up at the end of a sleep cycle-which has 90 minutes of proper REM sleep. When you wake up in the middle of a deep sleep, we end up feeling exhausted, tired and grumpy-because we feel we did not get proper sleep.

Detailed explanation-4: -An average sleep cycle lasts about 90 minutes. Ideally, you need four to six cycles of sleep every 24 hours to feel fresh and rested. Each cycle contains four individual stages: three that form non-rapid eye movement (NREM) sleep and one rapid eye movement (REM) sleep.

Detailed explanation-5: -[15] A complete sleep cycle takes roughly 90 to 110 minutes. The first REM period is short, and, as the night progresses, longer periods of REM and decreased time in deep sleep (NREM) occur.