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Getting enough sleep has long been considered a key to good mental and physical health. But some people are genetically predisposed to sleep less without feeling any less energetic.
Average Sleep Duration
Although sleep might seem like a “waste of time,” deliberately cutting it short can harm your health. The right amount of sleep, though, is still debated.
Some scientists argue that sleeping less than six hours reduces the benefits of physical exercise. Recent studies, however, suggest that healthy sleep duration can vary from person to person based on genetics.
Adequate sleep is vital for well-being and sound judgment. How much sleep you need can differ depending on age, lifestyle, and overall health. The National Sleep Foundation offers these general guidelines for healthy sleep:
- Newborns (0-3 months) – 14-17 hours daily;
- Infants (4-12 months) – 12-16 hours;
- Toddlers (1-2 years) – 11-14 hours;
- Preschoolers (3-5 years) – 10-13 hours;
- School-age children (6-12 years) – 9-12 hours;
- Teenagers (14-18 years) – 8-10 hours;
- Young adults (18-25 years) – 7+ hours.
According to the Centers for Disease Control and Prevention, older adults typically need slightly less sleep. For people aged 61-64, the optimal amount is 7-9 hours, while those 65 and older generally need 7-8 hours. Many seniors sleep less than they did when they were younger and often go to bed earlier and wake up sooner.
These are guidelines, not hard rules. Individual sleep needs can change across a year, a month, or even from day to day depending on how much rest a person needs to recharge.
Factors that influence sleep needs include physical activity, stress, diet, and overall health. Sleep quality is just as important as duration—insomnia can seriously reduce the benefits of a night’s rest.
Why Sleep Matters
Sleep has a deep evolutionary history. Systems that regulate sleep may have first developed in ocean-dwelling creatures to manage timing for surfacing and feeding.
Today, sleep plays a vital role in nearly all animals, including jellyfish and worms. Even bacteria, which don’t sleep in the conventional sense, show periods of reduced activity that resemble sleep.
In more complex animals, sleep has distinct stages and types. Many mammals, birds, reptiles, and some fish experience rapid eye movement (REM) sleep, which is tied to dreaming and supports learning and memory.
During sleep, most multicellular organisms repair muscles, organs, and cells. Sleep also strengthens the immune system by triggering chemicals that fight infection.
In animals with large brains, including humans, sleep plays a crucial role in memory consolidation by helping the brain process and store new information. Sleep also supports creativity, problem-solving, and attention, while insomnia can impair those abilities.
Sleep is especially important for children and teenagers because it supports growth and development. During sleep, the body produces hormones that promote growth and build muscle.
What Happens If You Don’t Get Enough Sleep?
Not getting enough sleep can harm overall health. Insomnia contributes to cognitive dysfunction, memory problems, and a weakened immune system. Chronic sleep loss also disrupts hormonal balance and can lead to weight gain and obesity.
Sleep deprivation often causes irritability and mood swings and raises the risk of chronic health problems. Overall, that leads to a lower quality of life. Still, a very small number of people can function well while sleeping much less than the average person.
Why Can Some People Sleep Less?
The difference appears to be written into their genes. Researchers have identified specific genetic variants linked to naturally short sleep.
As reported by Interesting Engineering, some of these genetic variants let people sleep just 4-6 hours a night throughout their lives without obvious health problems. They feel as energetic as people who get a full night’s rest.
Factors that disrupt sleep often make it hard to tell who naturally sleeps less and who uses stimulants to stay awake. In 2009, Professor of Neurology Ying-Hui Fu found that a mutation in the DEC2 gene allows some people to function on less sleep. In her study, people without the mutation averaged about 8 hours of sleep per night, while those with the mutation averaged about 6 hours.
Follow-up experiments in mice created the same mutation. The mutated mice slept less, woke more easily, and did not sleep for longer stretches.
Studies also suggest natural “short sleepers” may gain other advantages from this trait. They often appear more optimistic, have higher energy, and perform better at multitasking.
DEC2 isn’t the only gene linked to short sleep. Another mutation in the gene BHLHE41 is associated with shorter sleep without obvious health downsides; people with that mutation have a higher pain threshold and don’t experience jet lag as readily.
Some studies even hint that these short sleepers might live longer, though the reasons aren’t clear. Dr. Fu’s work is an important step toward understanding how sleep and health connect. Still, lacking one of these genes shouldn’t be taken as permission to habitually sleep just a few hours a night—consistent, sufficient sleep is important for most people’s health.
