Some people carry a gene that lets them thrive on just a few hours of sleep

A small number of people wake up fully rested after four to six hours of sleep, night after night, without the grogginess or health toll that short sleep normally brings. Researchers have traced this trait to specific, heritable gene mutations rather than willpower or training, and studying those genes is reshaping what scientists thought they knew about why humans need to sleep at all.

A Family of Early Risers Led to the DEC2 Discovery

The story began with a single family whose members consistently went to bed around 11 p.m. or midnight and woke up naturally near 5 a.m., feeling fully alert. In 2009, University of California, San Francisco neurologist Ying-Hui Fu identified a mutation in a gene called DEC2 shared by the short-sleeping members of that family but absent in relatives who slept a typical eight hours. Fu’s team described these individuals as people who were “born this way,” distinguishing them from night owls or larks who simply prefer different schedules while still needing a full night’s rest.

Fu’s lab later engineered mice to carry the identical human DEC2 mutation, allowing the researchers to test its effects directly rather than only observing it in people. The resulting study, published in the Proceedings of the National Academy of Sciences in March 2018, showed that mice with the mutation slept less than normal mice yet showed no signs of the memory or attention deficits that usually accompany sleep loss.

Orexin and the Molecular Switch Behind Shorter Sleep

DEC2 works by regulating orexin, a hormone that promotes wakefulness and is best known for its near-total absence in people with narcolepsy. Under normal circumstances, DEC2 rises during the day and suppresses a gene called MyoD1 that would otherwise drive orexin production, then fades before dawn so MyoD1 can switch orexin back on and prompt waking. The mutation found in human short sleepers weakens DEC2’s grip on MyoD1, so orexin gets produced in greater amounts and for longer stretches, which appears to let short sleepers stay awake and alert on less total rest. Fu described DEC2’s normal job as a timekeeper that matches orexin output to the body’s circadian rhythm, and the mutation appears to loosen that timing constraint rather than eliminate the need for sleep altogether.

A Second Gene, ADRB1, Turned Up in an Unrelated Family

DEC2 mutations are extremely rare, and Fu’s team spent roughly a decade searching for other genetic pathways that produce the same trait. That search led to a mutation in a gene called ADRB1, which encodes a receptor found in a brain region called the dorsal pons that helps regulate the sleep-wake cycle. UCSF’s account of the ADRB1 discovery describes how researchers again used mouse models carrying the human mutation and found that neurons with the altered receptor were more easily excited, making the mice more wakeful on less sleep, mirroring the pattern seen in the DEC2 family. The two genes act on separate biological pathways yet converge on the same outcome, which tells researchers that natural short sleep is not a single-gene fluke but rather one behavior with multiple possible molecular routes into it.

Why This Differs From Ordinary Sleep Deprivation

The distinction researchers emphasize most is that these mutation carriers are not simply tolerating less sleep the way a sleep-deprived person tolerates fatigue. People who chronically sleep less than they biologically need typically show measurable declines in memory consolidation, immune function, and cardiovascular health over time. Natural short sleepers with the DEC2 or ADRB1 variants do not show those same deficits in the studies conducted so far, and some carriers report feeling more energetic and resilient to schedule changes than typical sleepers. That resilience suggests the mutations do not just delay the negative effects of missing sleep but instead genuinely reduce the biological requirement for it, which is why Fu’s group continues to study these pathways for clues about the deeper purpose of sleep in the brain.

What the Research Could Eventually Explain

Because DEC2 and ADRB1 both intersect with circadian and arousal circuitry rather than any single “sleep center,” their discovery has pushed researchers toward viewing sleep need as a tunable trait shaped by several interacting genes rather than a fixed universal number. Fu’s lab has continued screening additional short-sleeping families for other variants, aiming to build a fuller genetic map of the trait. That map could eventually inform research into sleep disorders, aging, and conditions in which orexin signaling goes wrong, including narcolepsy, even though the immediate finding remains a description of a rare inherited trait rather than a treatment. The mutations remain uncommon enough that most people who function well on little sleep are not short sleepers in this genetic sense, and researchers caution that habitually cutting sleep short without carrying one of these variants still carries the usual health risks documented in decades of sleep science.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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