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99 free Sleep trivia questions with answers — science & nature quiz, new questions added Aug 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 99 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 REM-sleep paralysis produced by brainstem inhibition of motor neurons; when it fails, sleepers act out 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 covers it: the standard figure for an adult sleep cycle is 90 minutes, with the normal range stretching to about 110.
Q 05What is the body's internal process that regulates the sleep-wake cycle roughly every 24 hours called?
Circadian rhythm
The circadian rhythm is a natural, internal process that regulates the sleep-wake cycle and other bodily functions over an approximately 24-hour period.
Q 06What is the term for the drowsy transitional state while falling asleep, often with vivid imagery?
Hypnagogia
Hypnagogia is the drowsy state while falling asleep; its mirror image on waking is hypnopompia, and both can bring fleeting, harmless hallucinations.
Q 07Historian Roger Ekirch argued pre-industrial Western Europeans commonly slept in what pattern?
Two segments with a waking gap
The 'first sleep' and 'second sleep' were separated by an hour or so 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, often called deep sleep or slow-wave sleep, is essential for the body to repair and regrow tissues, build bone and muscle, and strengthen the immune system.
Q 10Which rare neurological disorder, mostly affecting adolescent males, causes recurring episodes of sleep lasting days or weeks?
Kleine–Levin syndrome
Kleine–Levin syndrome brings persistent episodic hypersomnia with cognitive and behavioural changes; it was added to the International Classification of Sleep Disorders in 1990.
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
Without light reaching the retina, the brain's master clock is never reset to the 24-hour day, so bedtime drifts later and later.
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, also called noctambulism, is a NREM parasomnia in which the sleeper walks in a blend of sleep and wakefulness, usually during deep sleep early in the night.
Q 22Which theory says dreams are the brain making sense of random neural activity in REM sleep?
Activation-synthesis theory
Activation-synthesis theory, proposed by Harvard psychiatrists J. Allan Hobson and Robert McCarley in 1977, treats dreams as the brain's story-making response to brainstem activation during REM sleep.
Q 23Which parasomnia, often with a felt presence or chest pressure, strikes while falling asleep or waking?
Sleep paralysis
A Texas cave: in 1972 Siffre spent 205 days in Midnight Cave, Texas, with no clocks or daylight, a decade after his two-month 1962 stay underground in the Alps.
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 15Which hormone, secreted in the brain at night, helps regulate the sleep-wake cycle?
Melatonin
Melatonin is primarily produced and released by the pineal gland in response to darkness, signaling to the body that it is nighttime and promoting sleep.
Q 16Fatal familial insomnia, an inherited disease that destroys the ability to sleep, belongs to which class of disorders?
Prion diseases
Prion diseases: FFI is caused by a D178N mutation in the prion protein gene PRNP on chromosome 20, the same gene behind Creutzfeldt-Jakob disease.
Q 17What disorder involves recurrent upper airway obstruction while a person is asleep?
Sleep apnea
Sleep apnea is a common sleep disorder where breathing repeatedly stops and starts during sleep, often due to obstruction of the upper airway.
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 19What is the most common sleep disorder, defined by persistent difficulty falling or staying asleep?
Insomnia
Insomnia is the most prevalent sleep disorder, characterized by difficulty falling asleep, staying asleep, or experiencing non-restorative sleep, leading to daytime impairment.
Q 20Which chronic neurological disorder is also known as Willis–Ekbom disease?
Restless Legs Syndrome
Restless Legs Syndrome, or Willis–Ekbom disease, is usually chronic and brings an uncontrollable urge to move the legs, typically from uncomfortable sensations at night or at rest.
Sleep paralysis is a temporary state of being unable to move or speak that occurs when a person is waking up or falling asleep, often accompanied by vivid hallucinations.
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) of the hypothalamus acts as the master circadian pacemaker in mammals, receiving light input from the retina and regulating daily rhythms.
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, also known as a sleep start, is a sudden, brief, and involuntary contraction of muscles that occurs as a person is falling asleep.
Q 30Which of the following is considered a good sleep hygiene practice?
Consistent bedtime and wake-up time
A consistent bedtime and wake-up time, even on weekends, is one of the most reliable ways to steady the body clock; caffeine, irregular hours and late intense exercise all disrupt sleep.