“REM sleep is an active time for the brain, and great for innovation, creativity and emotional regulation,” says Bostock. Each cycle repeats every 90 minutes. “People often assume they ...

or difficulty staying awake during the day Waking up multiple times during a single 90-minute sleep cycle Waking up earlier than you'd like and not being able to fall back asleep Note: Sleepiness ...

Stage 2 can last up to 50 minutes during the night’s first 90-minute sleep cycle. (It typically occupies a smaller portion of subsequent cycles.) Spindles can arrive every few seconds for a ...

This is also called the monophasic sleep cycle. Getting your rest all at once ... sleeping at night and taking a short nap or 60- to 90-minute siesta in the middle of the day, or breaking up ...