For most people, there is no safe way to permanently reduce how much sleep your body needs. The biological requirement for sleep is largely genetic, and the vast majority of adults need seven to nine hours. However, there are evidence-based ways to get more out of the sleep you do get, so you spend less time in bed tossing around and more time in genuinely restorative rest. That distinction, between needing less sleep and wasting less of it, is where the real opportunity lies.
Why Some People Naturally Need Less Sleep
A small number of people are genuinely wired to thrive on six hours or fewer. Researchers have identified several gene mutations responsible for this trait, which they call Familial Natural Short Sleep. Carriers of a mutation in the ADRB1 gene sleep about two hours less per night than non-carriers in the same family, roughly 132 fewer minutes. A mutation in the NPSR1 gene is associated with about 180 fewer minutes of sleep. And the first short-sleep gene discovered, DEC2, produces carriers who average 6.25 hours compared to 8.06 hours in their non-carrier relatives.
These mutations are rare. Fewer than one percent of people who claim to function well on minimal sleep actually carry one of these genetic variants. The rest are simply accumulating sleep debt without recognizing the cognitive toll. If you’ve always needed seven or eight hours and you’re hoping to train yourself down to five, your biology is working against you.
The Real Cost of Cutting Sleep Short
The Whitehall II Study, which tracked thousands of British civil servants over years, found that people who decreased their sleep duration showed lower scores on tests of reasoning, vocabulary, and general cognitive function. The magnitude of those deficits was equivalent to four to seven years of brain aging. That means a 35-year-old chronically sleeping too little can perform cognitively like someone in their early 40s.
One reason this matters is how sleep debt compounds. Your brain measures wakefulness through a molecule called adenosine, a byproduct of cellular activity that builds up the longer you’re awake. During sleep, adenosine gets cleared away, resetting your mental sharpness. Cut sleep short and that clearance is incomplete. The good news from the CDC’s sleep research: you don’t need to repay lost sleep hour for hour, because your body sleeps more deeply when it’s deprived. But if you’ve been undersleeping for many consecutive days, it can take several nights of quality rest to fully recover.
Sleep Efficiency: Getting More From Fewer Hours
Sleep efficiency is the percentage of time in bed that you actually spend asleep. If you lie down for nine hours but spend one of those hours staring at the ceiling, your efficiency is around 89 percent. Research considers 85 percent or lower to be poor sleep efficiency, and that threshold is linked to real health consequences. One study found that low sleep efficiency increased the odds of prehypertension 4.5-fold, even more than short sleep duration alone, which increased it 2.8-fold.
Improving your sleep efficiency is the closest thing to “needing less sleep” that actually works. If you currently spend eight and a half hours in bed to get seven hours of sleep, tightening that gap means you reclaim time without sacrificing rest. Several strategies directly target efficiency:
- Room temperature. Keeping your bedroom between 19 and 21°C (66 to 70°F) helps your body establish the skin temperature range of 31 to 35°C that promotes sleep. Even a shift of just 0.4°C in skin temperature within that range can shorten the time it takes to fall asleep and encourage deeper sleep stages.
- Consistent wake time. Your circadian rhythm anchors to when you wake up more than when you go to bed. A fixed wake time trains your body to consolidate sleep into a tighter, more efficient window.
- Daytime exercise. High-intensity exercise increases adenosine levels in the brain, which strengthens your sleep drive at night. This translates to falling asleep faster and spending more of your time in bed actually sleeping.
- Limiting long naps. Napping clears adenosine from the brain, which reduces your sleep pressure at night. If you’re trying to maximize nighttime efficiency, keep naps short (under 20 minutes) or skip them entirely.
Protecting the Sleep Stages That Matter Most
Not all sleep is equal. Adults should spend roughly 20 percent of their total sleep in deep slow-wave sleep, which works out to about 60 to 100 minutes per night. Deep sleep handles physical recovery, immune function, and brain maintenance. REM sleep, which supports memory, learning, and emotional processing, makes up another significant portion. When you cut total sleep time, REM sleep suffers disproportionately because it’s concentrated in the later hours of the night.
This is why sleeping six hours of high-quality, uninterrupted sleep is meaningfully better than sleeping seven hours of fragmented sleep. The goal isn’t just duration. It’s protecting the architecture of your sleep cycles so each stage gets adequate time.
Why Polyphasic Sleep Doesn’t Work
Polyphasic sleep schedules, like the Uberman (six 20-minute naps totaling two hours) or Everyman (one core sleep plus several naps), claim to compress your sleep needs dramatically. A consensus panel from the National Sleep Foundation reviewed the available evidence and found no support for these claims. Their conclusion was direct: polyphasic sleep schedules and the sleep deficiency built into them are associated with adverse physical health, mental health, and performance outcomes. The human brain needs sustained, consolidated sleep periods to cycle through its repair and memory-processing stages. Scattering naps across the day doesn’t replicate that.
Non-Sleep Deep Rest as a Supplement
Non-sleep deep rest, or NSDR, refers to practices like yoga nidra and guided body-scan relaxation that shift the nervous system from its stress mode into its recovery mode. During NSDR, brain activity can slow into patterns that overlap with early sleep stages, even though you remain technically awake. This can increase dopamine levels, lower heart rate and blood pressure, and reduce subjective fatigue.
NSDR is not a replacement for sleep. Researchers have not yet directly compared its restorative effects to those of a nap, let alone a full night’s rest. But as a tool for recovering from a rough night or sustaining alertness during the day, a 10 to 20 minute NSDR session can take the edge off sleep pressure without the grogginess that comes from longer naps.
Glycine and Sleep Quality
One nutritional intervention with solid evidence behind it is glycine, an amino acid. Taking 3 grams before bed has been shown to shorten the time it takes to reach deep sleep, reduce next-day sleepiness and fatigue, and subjectively improve sleep quality in people with insomnia tendencies or restricted sleep schedules. Importantly, it achieves this without altering overall sleep architecture, meaning it doesn’t knock you out or change your natural sleep pattern. It simply helps your body get to the restorative stages faster. Magnesium glycinate, a common supplement form, delivers both glycine and magnesium, which independently supports muscle relaxation.
What You Can Realistically Do
You probably can’t change how much sleep your body needs. But you can change how much of your time in bed is wasted. The practical path forward involves stacking several small improvements: cooling your room, exercising during the day, keeping a rigid wake time, limiting naps, and possibly adding glycine before bed. Each one shaves minutes off the time it takes to fall asleep or reduces nighttime awakenings, and together they can meaningfully compress the gap between time in bed and time asleep.
If you consistently feel rested and sharp after six or six and a half hours with no alarm clock, you may be one of the rare natural short sleepers. If you need an alarm to wake up, feel groggy for the first hour, or crash in the afternoon, your body is telling you it needs more than it’s getting. The most effective strategy isn’t fighting that signal. It’s making sure every hour of sleep you get actually counts.