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148 free Sleep trivia questions with answers — science & nature quiz, new questions added Oct 2026.
57 free sleep trivia questions with answers. How well do you understand the science of sleep? Test your knowledge with our comprehensive sleep trivia quiz covering everything from sleep cycles and disorders to fascinating facts about dreams. Whether you're a sleep expert or just curious about rest, this quiz will challenge what you think you know about one of life's most essential activities.
30 of 148 questions with answers and explanations. Play the quiz
Q 01Dolphins sleep with one eye open; what is this slow-wave sleep pattern called?
Unihemispheric
Unihemispheric slow-wave sleep lets one half of the brain rest while the other stays alert; the eye opposite the sleeping half shuts while the other stays open to keep watch or keep surfacing to breathe.
Q 02What is the term for the temporary muscle paralysis that normally occurs during REM sleep?
Atonia
Atonia is the muscle shutdown of REM sleep, produced by brainstem inhibition of motor neurons; when it fails, sleepers act out their dreams, the hallmark of REM sleep behavior disorder.
Q 03Roughly how long did 17-year-old Randy Gardner stay awake for his famous 1964 record?
11 days
11 days: Gardner stayed awake about 264 hours ending 8 January 1964, observed by Stanford sleep researcher William Dement, and recovered after a few long sleeps.
Q 04Roughly how long does one complete adult sleep cycle, through NREM and REM, last?
90-110 minutes
90-110 minutes is one pass from light sleep through deep sleep to REM, repeated four to six times a night; REM periods lengthen toward morning, so a short night cuts REM sleep most.
Q 05In which country is inemuri, dozing off in meetings, classes or on the train, widely tolerated?
Japan
Japan: inemuri joins the words for 'being present' and 'sleep', and a nap in a meeting can be read as proof that someone has worked themselves to exhaustion.
Q 06What is the term for the drowsy transitional state while falling asleep, often with vivid imagery?
Hypnagogia
Hypnagogia is the slide into sleep and hypnopompia its mirror on waking; Salvador Dali and Thomas Edison credited it with ideas, and a 2021 study found a brief dip into it boosted puzzle-solving insight.
Q 07Historian Roger Ekirch argued pre-industrial Western Europeans commonly slept in what pattern?
Two segments with a waking gap
Two segments with a waking gap: a 'first sleep' and 'second sleep' were split by an hour or more around midnight that people used for prayer, chores, sex or conversation.
Q 08Which NREM Stage 2 EEG waveform, a sharp negative then slow positive wave, may follow a sudden noise?
K-complex
K-complexes are large, distinct waveforms primarily seen during NREM Stage 2 sleep, which can occur spontaneously or in response to external stimuli, and are thought to help protect sleep and aid memory.
Q 09Which part of the night's sleep is the deepest and most restorative for tissue repair and immunity?
NREM Stage 3
NREM Stage 3, or slow-wave sleep, is when the body repairs tissue and bolsters immunity; it is packed into the first half of the night, so the early hours of sleep do most of the repair work.
Q 10Which rare neurological disorder, mostly affecting adolescent males, causes recurring episodes of sleep lasting days or weeks?
Kleine–Levin syndrome
Kleine–Levin syndrome can have a teenager sleeping up to 20 hours a day for weeks, yet between episodes they are entirely well, and the attacks usually fade away with age.
Q 11Non-24-hour sleep-wake disorder, where the body clock drifts free of the day, is especially common in people with what?
Total blindness
Total blindness leaves no light reaching the retina, so the brain's master clock is never reset to the 24-hour day and the urge to sleep drifts a little later each night.
Q 12What term describes a sudden, brief loss of muscle tone triggered by strong emotion, such as laughter?
Cataplexy
Cataplexy, a hallmark of type 1 narcolepsy, leaves the person fully conscious during an attack, which can range from a drooping jaw to complete collapse.
Q 13Where did body-clock researcher Michel Siffre spend six months of 1972 in isolation?
In a Texas cave
Q 21What is the medical term for sleepwalking?
Somnambulism
Somnambulism arises from deep sleep early in the night, not from dreams; despite the eyes-closed, arms-out cliche, a sleepwalker's eyes are open, and they rarely recall the episode.
Q 22Which theory says dreams are the brain making sense of random brainstem signals in REM sleep?
Activation-synthesis theory
Activation-synthesis theory, from Harvard psychiatrists Allan Hobson and Robert McCarley in 1977, holds that the forebrain builds each dream by matching random brainstem signals against stored memories.
Q 23Which sleep disorder, often with a felt presence or chest pressure, strikes while falling asleep or waking?
Sleep paralysis
In a Texas cave: Siffre lived about six months of 1972 in Midnight Cave with no clock or daylight, and his body at times slipped onto a 48-hour day that he could not tell from a normal one.
Q 14REM sleep behavior disorder, acting out dreams, is a strong early predictor of which condition?
Parkinson's disease
Parkinson's disease: RBD can begin years or decades before tremor and stiffness, and a majority of people with RBD go on to develop Parkinson's or a related synucleinopathy.
Q 15In classical myth, which underworld river flows through the cave of the god of sleep?
Lethe
Lethe: Ovid has its waters trickle over pebbles at the foot of Sleep's cave, their murmur inviting slumber; in myth, anyone who drank from the river forgot everything.
Q 16Fatal familial insomnia, an inherited disease that destroys the ability to sleep, belongs to which class of disorders?
Prion diseases
Prion diseases: in FFI a misfolded protein, from the same gene behind inherited Creutzfeldt-Jakob disease, destroys the thalamus, so sleep fails entirely and death follows within months to a few years.
Q 17What disorder involves recurrent upper airway obstruction while a person is asleep?
Sleep apnea
Sleep apnea can stop a sleeper's breathing more than 30 times an hour in severe cases; each pause ends in a brief arousal they rarely remember, so a bed partner often notices first.
Q 18Which chronic neurological condition causes overwhelming daytime sleepiness and sleep attacks?
Narcolepsy
Narcolepsy: type 1 involves the loss of roughly 70,000 orexin (hypocretin) neurons in the hypothalamus, which is why low orexin in spinal fluid confirms the diagnosis.
Q 19Which is the most common sleep disorder among adults?
Insomnia
Insomnia is the most common sleep complaint, and the first-line treatment is not a pill but CBT-I, a short course of therapy that retrains habits and beliefs about sleep.
Q 20Which chronic neurological disorder is also known as Willis–Ekbom disease?
Restless Legs Syndrome
Restless Legs Syndrome, or Willis–Ekbom disease, brings an urge to move the legs that builds at rest in the evening and eases with walking; low iron in the brain is one known driver.
Sleep paralysis happens when the muscle shutdown of REM sleep lingers into waking, so the mind is alert while the body cannot move; episodes pass within a few minutes.
Q 24Chronic sleep deprivation significantly increases the risk of which of the following health conditions?
Type 2 diabetes
Type 2 diabetes: people on restricted sleep clear glucose more slowly and show reduced insulin sensitivity, and habitual short sleep is also tied to weight gain and heart disease.
Q 25In 1953, graduate student Eugene Aserinsky discovered REM sleep while working at which institution?
University of Chicago
University of Chicago: Aserinsky, working under Nathaniel Kleitman, spotted the rapid eye movements of sleeping subjects there; their 1953 Science paper founded modern sleep research.
Q 26What is the recommended sleep duration for adults aged 18 to 64 per night?
7-9 hours
7-9 hours is the National Sleep Foundation's 2015 recommendation for adults 18-64; newborns need 14-17 hours, and habitual sleep under seven hours is linked to coronary heart disease.
Q 27Which brain structure is the master pacemaker of the mammalian circadian clock?
Suprachiasmatic nucleus (SCN)
The suprachiasmatic nucleus (SCN) sits just above the crossing of the optic nerves, so it gets light signals straight from the eyes; people with damage to it sleep erratically across the day.
Q 28What other name for REM sleep did French researcher Michel Jouvet coin in 1959?
Paradoxical sleep
Paradoxical sleep: the EEG looks almost like waking, rapid and low-voltage, while the voluntary muscles are switched off; Michel Jouvet coined the term in 1959.
Q 29What is the sudden, involuntary muscle twitch that can occur just as a person is falling asleep?
Hypnic jerk
A hypnic jerk, or sleep start, often comes with a sensation of falling; most people get them now and then, and caffeine, stress or fatigue make them more frequent.
Q 30Which of these habits do sleep-hygiene guidelines recommend?
Consistent bedtime and wake-up time
A consistent bedtime and wake-up time, weekends included, steadies the body clock; a nightcap fragments the second half of the night, and after 20 minutes awake the advice is to get out of bed.