AP PSYCHOLOGY

Detailed explanation-1: -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-2: -“There’s an idea that everyone sleeps in 90-minute cycles but that’s an average, not a rule, ” says Winter. “That means your REM cycle might be longer or shorter than 90 minutes. So you shouldn’t feel like you’ll wake up feeling more restored if you wake up five minutes later or earlier.” Phew.

Detailed explanation-3: -For our purposes, it suffices to say that one sleep cycle lasts an average of 90 minutes: 65 minutes of normal, or non-REM (rapid eye movement), sleep; 20 minutes of REM sleep (in which we dream); and a final 5 minutes of non-REM sleep.

Detailed explanation-4: -What Is REM Sleep? Usually, REM sleep happens 90 minutes after you fall asleep. The first period of REM typically lasts 10 minutes. Each of your later REM stages gets longer, and the final one may last up to an hour.