Your brain can function on 5 hours of sleep, but it's generally not optimal, leading to impaired focus, memory, decision-making, and mood, with most adults needing 7-9 hours for peak performance as sleep deprivation negatively impacts cognitive abilities and increases risks for accidents, similar to alcohol impairment. While a rare few might genetically thrive on less, chronic 5-hour sleep often results in deficits, even if you don't feel overly tired.
A minimum of 7 hours of daily sleep seems to be necessary for proper cognitive and behavioral function. The emotional and mental handicaps associated with chronic sleep loss as well as the highly hazardous situations which can be contributed to the lack of sleep is a serious concern that people need to be aware of.
Short answer: Many people can function on 5 hours of sleep for short periods, but it is suboptimal for health, cognition, and long-term performance. Regularly getting only 5 hours increases risks and reduces resilience; occasional short nights are manageable, chronic restriction is not.
Five hours of sleep in a given night will normally be okay provided that you are used to getting adequate rest. The body is actually quite strong and a single night should not cause any severe damage. Sleep experts recommend that most of the adults should sleep 7 -9 hours every night.
Give it time: Remember that it can take days to recover from a sleep debt. Increase your sleep time slowly, by 15 to 30 minutes at a time, until you reach the optimal amount of sleep for your body. Focus on improving your sleep hygiene and consistently getting enough sleep, and your body will do the rest.
Having short sleep durations, particularly less than 7 hours per night is associated with increased risk of cardiovascular disease morbidity and mortality.
The koala is famous for sleeping around 20-22 hours a day, which is about 90% of the day, due to their low-energy diet of eucalyptus leaves that requires extensive digestion. Other extremely sleepy animals include the sloth (up to 20 hours) and the brown bat (around 20 hours), with some snakes like the ball python also sleeping up to 23 hours daily.
Signs of poor core sleep (deep, restorative sleep) include waking up foggy, daytime fatigue/energy crashes, poor concentration, irritability, frequent illness, memory issues, and mood swings, indicating your brain and body aren't fully repairing and consolidating memories. You might also experience increased sugar cravings, slow muscle recovery, and a weakened immune system.
Once a baby is around 6 months and no longer requires nighttime feedings [1], they may be physiologically able to sleep for longer stretches at night. Many babies at this age are capable of sleeping through the night (meaning sleeping for at least 6 uninterrupted hours without calling out for help from a caregiver).
Researchers continue to study the causes of short sleeper syndrome. They've identified gene changes in natural short sleepers. Researchers believe these genetic changes make it possible for people with SSS to feel refreshed with less sleep.
Yes, the Navy SEAL sleep trick (an 8-minute power nap with elevated legs) is a real technique for quick rest, popularized by former SEAL Jocko Willink, that helps improve alertness and reduce fatigue, though its effectiveness depends on individual relaxation skills and it's not a substitute for full nighttime sleep. The method involves lying down, elevating your feet above your heart (on a chair or couch), relaxing facial muscles, dropping shoulders, and clearing your mind for about 8-10 minutes to promote relaxation and blood flow, preventing grogginess.
This time allows the body to go through 4-5 sleep cycles, with deep sleep aiding physical recovery and REM sleep assisting in mental, memory, and emotional restoration. Therefore, sleeping 5 hours each night is not enough to maintain health and work productivity.
A large new study published provides evidence that people 50 and older who sleep five hours or less at night have a greater risk of developing multiple chronic diseases as they age compared with peers who get a longer night's rest.
Einstein slept nearly 10 hours a day. He was known to be a firm believer in the importance of a good night's sleep, often aiming for around 10 hours of rest. However, his approach to sleep was somewhat unconventional.
About 75% of your brain is water, making hydration crucial for sharp thinking, focus, and mood, as even mild dehydration (losing 2% of body water) can impair memory, concentration, and reaction time. The remaining part of the brain is mostly fat, and this water content is essential for creating neurotransmitters and supporting brain function.
The 3-2-1 sleep rule is a simple wind-down routine: stop eating and drinking alcohol 3 hours before bed, stop working/mentally stimulating activities 2 hours before, and turn off screens (phones, TVs) 1 hour before sleep, helping you transition to rest by reducing stimulants and preparing your mind and body. It's often part of a larger 10-3-2-1-0 rule, which also adds no caffeine 10 hours prior and no hitting snooze (0) in the morning.
This is sometimes described as a period of 'quiet wakefulness'. But is taking a quick rest - closing your eyes, putting your feet up and clearing your mind for a couple of minutes - as beneficial as getting some sleep? The concise answer is 'no'.
7 Common Signs That You Don't Have Enough Deep Sleep
For adults, getting less than seven hours of sleep a night on a regular basis has been linked with poor health, including weight gain, having a body mass index of 30 or higher, diabetes, high blood pressure, heart disease, stroke, and depression.
Gen Z stays up late due to a combination of technology (blue light, endless content), significant stress and anxiety (FOMO, financial/global worries), biological shifts (natural teenage circadian rhythm), and "revenge bedtime procrastination," where they sacrifice sleep for personal time, often in bed, scrolling social media. This digital-heavy, high-stress lifestyle creates overstimulation and a misalignment with natural sleep patterns, leading to chronic sleep deprivation, notes the American Academy of Sleep Medicine and the Sleep Health Foundation.
The rarest major sleeping position is often cited as the Starfish (on your back with arms up), with only about 5-7% of people sleeping that way, but stomach sleeping (prone position) is also very uncommon, with less than 10% of adults preferring it, making it a strong contender for rarest, though sometimes considered a major type, not just a variation. More niche or minor variations, like specific fetal or "T-Rex arms" (bent wrists), might be rarer still, but data focuses on broad categories.
Among the most rested countries surveyed by Sleep Cycle, an app that tracks how much shuteye people are getting, New Zealand comes top with the average Kiwi clocking up in excess of 7.5 hours per night. Finland, the Netherlands, Australia, the UK and Belgium all rank highly for sleep, too, with Ireland close behind.
The answer is “probably.” Research has shown that many animals experience a sleep phase similar to humans known as REM (Rapid Eye Movement) sleep, which is closely associated with dreaming. This phase is characterized by increased brain activity and is when most vivid dreams occur.