Sleep is a state of reduced mental and physical activity. Body alternates between REM and non-REM sleep cycles. Sleep occurs in repeating periods lasting 90 minutes. Dreams occur during certain sleep stages
PSQI is a one-month sleep quality questionnaire developed by University of Pittsburgh researchers. Published in 1989, cited in over 34,000 peer-reviewed articles. Widely used in both clinical and research settings
Adults need 7-8 hours, teens 8-10 hours, children 9-11 hours sleep. Chronic sleep deprivation leads to drowsiness, depression, and memory problems. Sleep deprivation can cause weight gain, irritability, and concentration difficulties. Adults sleeping 4-5 hours have 30-40% higher risk of chronic diseases
Sleep apnea, narcolepsy, and chronic fatigue syndrome can cause morning sleepiness. Sleep paralysis may occur during waking or falling asleep
Rumination about past events is a major cause of nighttime depression. Nighttime light exposure may interfere with sleep cycles. Circadian rhythm disruption increases depression risk. Chronotype (sleep patterns) affects depression risk. Loneliness can cause sadness at night
Sleep paralysis is temporary inability to move or speak during sleep transition. Hallucinations occur during sleep paralysis, affecting three out of four people. Hallucinations can be visual, auditory, olfactory, or tactile. Symptoms include inability to move, limited eye movement, and out-of-body experiences