Any assertion that is not based on science, even though in some circumstances attempts are made to appear scientific.
Periodic psychological fluctuations.
Biological rhythms that occur approximately every 24 hours.
What kind of biological rhythm is the sleep-wake cycle?
Biological rhythms that occur more than once each day.
What kind of biological rhythm are the sleep stages?
Biological rhythms that occur once a month or once a season.
What kind of biological rhythm is the menstrual cycle?
Sleep researcher who coined the term "rapid eye movement" (REM).
Hormone that helps regulate daily biological rhythms.
Machine that amplifies and records waves of electrical activity that sweep across the brain's surface; electrodes placed on the scalp measure these waves.
REM (rapid eye movement) sleep
Recurring sleep stage during which vivid dreams commonly occur; also known as "paradoxical sleep", because muscles are relaxed but other body systems are active.
Recurring problems in falling asleep or staying asleep.
Sleep disorder characterized by temporary cessations of breathing during sleep and consequent momentary reawakenings.
Sleep disorder characterized by uncontrollable sleep attacks; the sufferer may lapse directly into REM sleep, often at inopportune times.
Sleepwalking, which usually starts in the deeper stages of non-rapid eye movement (N-REM) sleep; the sleepwalker can walk and talk and is able to see but rarely has any memory of the event.
Sleep-related problem characterized by high arousal and an appearance of being terrified; unlike nightmares, occurs during Stage 4 sleep, occurs within 2 or 3 hours of falling asleep, and are seldom remembered.