front 1 Circadian rhythm | back 1 the body's internal 24-hour clock that regulates the sleep-wake cycle |
front 2 Dreams | back 2 a subjective experience that most commonly occur during REM sleep, and can be caused by the brain processing daily information, re-experiencing memories, or other random signals |
front 3 Electroencephalograph (EEG) | back 3 a medical test that measures the electrical activity of the brain |
front 4 Hypersomnia | back 4 a condition characterized by excessive daytime sleepiness, where individuals may feel tired and have a strong need to sleep even after getting adequate rest |
front 5 Insomnia | back 5 a sleep disorder characterized by difficulty falling or staying asleep, leading to daytime fatigue and irritability |
front 6 Melatonin | back 6 a hormone that helps regulate the sleep-wake cycle, and it is also available as a supplement to help with sleep problems like insomnia and jet lag |
front 7 Napping | back 7 a short sleep during the day that can boost mood, alertness, and productivity |
front 8 Narcolepsy | back 8 a chronic sleep disorder characterized by excessive daytime sleepiness and sudden "sleep attacks" that significantly impact daily life |
front 9 Night Terrors | back 9 episodes of screaming, thrashing, and panic that occur during deep sleep, causing the person to seem terrified but remain unresponsive to being woken |
front 10 Nightmares | back 10 disturbing dreams that can cause feelings of fear, anxiety, or sadness, and often cause the sleeper to wake up |
front 11 Parasomnia | back 11 a sleep disorder characterized by abnormal behaviors, movements, or experiences that occur during sleep or while transitioning between sleep and wakefulness |
front 12 Restless Legs Syndrome | back 12 a neurological disorder causing an irresistible urge to move your legs, often accompanied by uncomfortable sensations like crawling, tingling, or aching |
front 13 Sleep | back 13 a vital biological process that allows the body and brain to rest and repair, cycling through different stages to consolidate memories, maintain physical health, and regulate hormones |
front 14 Sleep apnea | back 14 a disorder where breathing repeatedly stops and starts during sleep, causing poor sleep quality and potential health complications |
front 15 Sleep deprivation | back 15 when you aren't sleeping enough, or you aren't getting good, quality sleep |
front 16 Sleep paralysis | back 16 temporary inability to move or speak while waking up or falling asleep, often accompanied by terrifying hallucinations or a feeling of pressure on the chest |
front 17 Sleep study | back 17 a medical test that records brain waves, heart rate, oxygen levels, and other body functions while you sleep |
front 18 Snoring | back 18 the sound of obstructed breathing during sleep, caused by relaxed throat tissues vibrating as air passes through the airway |
front 19 Stage 1 (Non-REM) sleep | back 19 the initial, light stage of sleep that transitions you from wakefulness to sleep |
front 20 Stage 2 (Non-REM) sleep | back 20 a light stage of sleep where the heart rate and breathing slow down, the body temperature drops, and eye movements stop |
front 21 Stage 3 (Non-REM) sleep | back 21 the deepest stage of sleep, where the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system |
front 22 Stage 4 (REM Sleep) | back 22 the final and most active stage of the sleep cycle |
front 23 Somnambulism | back 23 sleepwalking |
front 24 Wakefulness | back 24 the state of being awake, alert, and conscious of one's surroundings |