Sleeping a lot (more than 9 hours regularly) can disrupt your body's internal clock, leading to daytime grogginess, poor memory, and increased fatigue, while also being linked to serious health issues like depression, heart disease, diabetes, obesity, chronic pain, and a higher risk of mortality, though it might be a symptom of an underlying problem like sleep apnea or depression rather than the direct cause. Consistently oversleeping can harm your brain function, immune system, and metabolic health, making you feel worse, not better.
Your body follows a natural internal clock that regulates sleep and wakefulness. Sleeping too much can throw off this cycle, making it harder to wake up feeling refreshed. Sleeping longer than necessary can lead to sleep inertia, a state of grogginess and sluggishness that occurs when waking up from deep sleep.
Oversleeping is associated with many health problems, including:
“Can I sleep too much” is a common question. Epidemiologic data indicate that people who habitually sleep more than 10 h at night are at greater risk of death and other effects [e.g., (Kripke, 2004)].
Your ideal wake up time should be no less than seven hours after your bedtime, and allow you to get as much rest as you need while still suiting your schedule, Harris notes. “The No. 1 thing is getting seven to nine hours per night," says Barone.
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.
Hypersomnia is excessive sleepiness. There are many causes of excessive sleepiness, including insufficient or inadequate sleep, sleep disorders, medications and medical or psychiatric illnesses. The characteristics of hypersomnia vary from one person to the next depending on age, lifestyle and underlying causes.
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.
Oversleeping and cognitive decline
The risk of developing a cognitive disorder is also significantly raised when sleep duration is longer than 10 hours, with increased duration significantly elevating the risk of cognitive disorders in non-demented elderly.
It recharges us with new energy
Your tired eyes need to close for a few hours while your brain “cleans itself up” and your body produces many new cells!
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.
While every organ in the body is affected by poor sleep, the brain takes the biggest hit, showing signs of dysfunction faster than any other system. Over time, the heart, liver, and immune system also begin to show stress, which can increase your risk of chronic illness.
Try to:
Vitamin B12 Deficiency: A Rare Cause of Excessive Daytime Sleepiness | Journal of Clinical Sleep Medicine.
While getting extra rest occasionally isn't usually a cause for concern, consistently oversleeping can be linked to underlying health issues, such as depression, sleep disorders, or chronic illness. It may also contribute to daytime grogginess, headaches, and increased risk for certain health problems.
Anything over 9 hours of sleep is considered oversleeping.
Oversleeping affects people who regularly get much more sleep than their body physically requires. This doesn't apply to extra sleep experienced while overcoming illness, jetlag or extreme workouts.
The 5-3-3 rule is a baby sleep training method for night weaning and fostering independent sleep, involving a baby sleeping 5 hours, staying awake for 3 (for a feed if needed), then sleeping another 3 hours, and continuing in 3-hour increments, teaching them to self-soothe after the initial long stretch, though it's a flexible guideline, not strict; it aims to create longer stretches for parents while meeting the baby's needs, often used around 4-6 months.
The 40s and 50s
Both fluctuations can result in lower energy levels, feeling lethargic, and less muscle mass. Again, the 40s and 50s impact people differently, with some noticing fewer effects than others. However, during this stage, people will usually notice they're "getting old".
Depending on one's age and individual needs, the National Sleep Foundation (USA) states that adults need seven to nine hours of good quality sleep per night to remain healthy and alert. School-age children require between nine and eleven hours, while older adults may need only seven to eight.
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.
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.