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97 free Sleep and Dreams trivia questions with answers — science & nature quiz, new questions added Aug 2026.
11 free Sleep and Dreams trivia questions with answers. Sleep and Dreams trivia lives in two places on BrainPickle. This page is the shorter set; the main quiz is Sleep trivia, with our deepest question pool on the topic and a source behind every answer.
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Q 01Roughly how long after falling asleep does the first REM episode begin?
70 minutes
70 minutes in, the first REM episode starts, and it is usually the shortest of the night at only a few minutes; a typical adult has four to five REM periods before waking.
Q 02During which stage of sleep does temporary muscle paralysis, known as atonia, typically occur?
REM Sleep
REM atonia is a protective mechanism during rapid eye movement (REM) sleep that prevents individuals from physically acting out their vivid dreams.
Q 03In 2007 the American Academy of Sleep Medicine cut the NREM sleep stages from four to how many?
Three
The old stages 3 and 4 were merged, so a modern sleep study reports three NREM stages plus REM.
Q 04Approximately how long does one complete sleep cycle typically last in adults?
90-110 minutes
An average sleep cycle, which includes all NREM and REM stages, lasts about 90 to 110 minutes, and most adults go through 4 to 6 cycles per night.
Q 05Which pair of EEG features is characteristic of NREM Stage 2?
Spindles and K-complexes
Spindles and K-complexes: a K-complex is the single largest event in a healthy human EEG, and a sound or a touch can trigger one without waking the sleeper.
Q 06Which of these is secreted most heavily during NREM Stage 3, the deepest stage of the night?
Growth hormone
Growth hormone: its largest pulse of the day comes during the slow-wave sleep of the first hours of the night, which is why deep sleep matters for tissue repair and growth.
Q 07REM sleep, the stage most associated with dreaming, takes up roughly what share of an adult's total sleep?
20–25%
20–25% of an adult's sleep is REM, but newborns spend far more of their sleep in it, one reason researchers think it helps the developing brain.
Q 08As the night progresses, how does the proportion of REM sleep typically change within each sleep cycle?
It lengthens
Early sleep cycles have shorter REM periods and longer deep sleep, but as the night progresses, REM stages become progressively longer.
Q 09What other name is NREM Stage 3 sleep known by, thanks to its characteristic brain waves?
Slow-wave sleep
The presence of large, slow delta waves on an EEG during NREM Stage 3 leads to its alternative name, slow-wave sleep (SWS).
Q 10Which neurotransmitter is abundant during REM sleep while serotonin and norepinephrine are nearly absent?
Acetylcholine
Acetylcholine: cholinergic cells in the pons switch REM on while the serotonin and norepinephrine cells fall silent, and the missing norepinephrine is one reason dreams so rarely reach lasting memory.
Q 11What is the scientific study of dreams called?
Oneirology
Oneirology, from the Greek oneiros for dream, is the scientific study of dreams; dream interpretation itself dates back to the Sumerians and Babylonians in the third millennium BCE.
Q 12Roughly how much time does a human spend dreaming each night?
More than two hours
Individual dreams last around 5 to 20 minutes each.
Q 13Across Calvin Hall's 50,000-plus dream reports, which emotion turned up most often?
Anxiety
Anxiety was the most common emotion in Hall's dream reports, with negative emotions outnumbering positive ones overall; sexual dreams, by contrast, made up no more than 10% of reports.
Q 21Horses can sleep standing up, but must lie down for short periods to get which kind of sleep?
REM
REM brings muscular atony, so a standing animal would collapse.
Q 22Who coined the term 'lucid dream' in a 1913 article?
Frederik van Eeden
Frederik van Eeden coined 'lucid dream' in his 1913 paper A Study of Dreams, using 'lucid' in the sense of having insight, as in a lucid interval.
Q 23Lucid-dreaming pioneer Stephen LaBerge did his dream research at which Californian university?
Stanford
Stanford: LaBerge earned his doctorate there and ran his lucid-dream studies in its sleep lab, finding that dream awareness and dream control are correlated but neither requires the other.
Q 14Which phase of sleep did Aserinsky and Kleitman's 1953 paper establish and tie to dreams?
REM sleep
Their discovery, published in Science, was the turning point for modern dream research.
Q 15According to Freud, dreams serve what purpose for the sleeper?
Prolonging sleep by presenting wishes as fulfilled
Prolonging sleep by presenting wishes as fulfilled: Freud called dreams the guardians of sleep, disguised fulfilments of repressed wishes, and cared more about interpreting them than explaining how they arise.
Q 16In Greek myth, which god of dreams sent warnings and prophecies to people sleeping at shrines and temples?
Morpheus
Morpheus delivered his messages to sleepers at shrines; early Greeks believed gods entered a sleeper's room through the keyhole.
Q 17In 1964, 17-year-old Randy Gardner set a record by staying awake for roughly how long?
Eleven days
Eleven days: Gardner stayed awake 264 hours in January 1964 without stimulants, monitored by a Navy doctor and sleep researchers, and slept just under 15 hours once it was over.
Q 18Why did Guinness World Records stop accepting sleep-deprivation record attempts?
Safety reasons
Safety reasons ended it: the record then stood at 18 days and 21 hours, held by Robert McDonald, after Randy Gardner's mark had been broken repeatedly.
Q 19Which mammal sleeps the longest, roughly 20 to 22 hours daily?
Koala
Koala: a diet of low-energy eucalyptus leaves keeps it dozing 20 to 22 hours a day, about as long as any mammal sleeps; bats are the only serious rival.
Q 20Which sleep pattern lets ducks at a flock's edge keep one eye open for threats?
Unihemispheric sleep
Unihemispheric sleep: one half of the brain rests while the other stays alert, so ducks on the edge of a flock do more of it and react to threats seen by the open eye.
Q 24In narcolepsy, the sudden loss of muscle tone triggered by strong emotion is called what?
Cataplexy
Cataplexy, the emotion-triggered loss of muscle tone, is the hallmark of type 1 narcolepsy, which is linked to low levels of the neuropeptide orexin in cerebrospinal fluid.
Q 25Which virus is thought to trigger the autoimmune process behind narcolepsy in susceptible people?
H1N1 influenza
H1N1 influenza: narcolepsy cases rose after the 2009 H1N1 pandemic and the Pandemrix vaccine, and the resulting immune attack destroys the neurons that produce orexin.
Q 26Sleepwalking occurs during which stage of sleep?
Slow-wave NREM
Slow-wave NREM: sleepwalking is a partial arousal out of deep sleep, which is why it usually happens in the first third of the night, when deep sleep dominates.
Q 27What is the medical term for sleepwalking?
Somnambulism
Somnambulism is also called noctambulism; its cousin somniloquy is sleep-talking, and bruxism is teeth-grinding.
Q 28One of the most common hallucinations during sleep paralysis is the presence of what?
An incubus pressing on the chest
An incubus pressing on the chest is the classic sleep-paralysis hallucination, often with a sensed presence in the room; between 8% and 50% of people experience sleep paralysis at some point.
Q 29The word 'circadian' derives from Latin words meaning what?
Approximately one day
Approximately one day: circa diem, a term coined by Franz Halberg in 1959; external cues that reset the clock, such as light and temperature, are called zeitgebers.
Q 30In 1729, de Mairan showed an internal clock exists by keeping which plant in constant darkness?
Mimosa pudica
Mimosa pudica: in constant darkness its leaves kept opening and closing on a roughly 24-hour pattern with no daylight cue, the first recorded evidence of an internal clock.