NREM sleep Non-Rapid Eye Movement sleep, or NREM, consists of three stages. Stage 1 is described as "drowsy sleep" or "somnolence" and is characterized by breathing rates becoming increasingly more consistent, the beginning of a decrease in muscle activity, and a decrease in heart rate. The typical duration of Stage 1 is around 10 minutes and accounts for approximately 5% of an individual's total sleep. Stage 2 is characterized by a further decline in muscle activity accompanied by a fading sense of consciousness of surroundings. Brain waves during Stage 2 are seen in the theta range. Stage 2 accounts for approximately 45-50% of an individual's total sleep. Stage 3 is the final stage of NREM sleep and the most common for parasomnias to occur. Also known as slow wave sleep (SWS), Stage 3 is characterized by brain temperature, respiratory rate, heart rate, and blood pressure being measured at their lowest. Representing approximately 15-20% of an individual's total sleep, brain waves during this stage are seen in the delta range. When an individual awakes during this stage, they are likely to exhibit grogginess and require up to thirty minutes to regain normal function and consciousness.
Sleep sex
Sleep and weight
Sleep onset
Sex after pregnancy
Prenatal perception
Menstrual leave
Nightmare
Sexual motivation and hormones