Why Science Says We May Not All Need 8 Hours of Sleep

Feel rested after less than 8? There’s a gene for that.

By: Archana Ram

Plenty of research has been devoted to how much sleep we need — and what happens when we don’t get enough. But most of us don’t need a study to tell us the frustrating side effects of less-than-stellar sleep. Cue the brain fog, cravings for junk food, sluggish feeling, you name it.

That’s because sleep is linked to everything from cognition and gut health to metabolic disorders. And while the conversation usually focuses on a lack of sleep, did you know getting too much can be problematic, too? In fact, research suggests that oversleeping is linked to type-2 diabetes, heart disease, and obesity.

Confused? Don’t be. We’ll help you find your sleep sweet spot and make sense of the science.

What Science Says About How Much Sleep We Need 

Sleeping in and waking up happy

You’ve probably heard the old saying to “get your 8 hours.” Everyone from the CDC to the National Sleep Foundation recommends that adults, including young adults, need 7 to 9 hours for optimal health. But if you feel well-rested and ready to take on the day with fewer hours, there may be a reason that’s deeper than you think.

In 2009, neurologists at UCSF identified what they called a “short sleep gene” — dubbed DEC2. Those with the gene feel just as rested with 6 hours of sleep compared to those who get 8 hours. Then in 2019, the same researchers found another gene, ADRB1, with a similar influence. People with ADRB1 could get by with fewer hours of sleep and didn’t just feel rested — they tended to be more optimistic, energetic, and adept at multitasking and also had a higher threshold for pain. They were even less affected by jet lag.

And as it turns out, if you tend to get sleepy earlier than most, that could be a biological quirk, too. Researchers have found that at least 1 in 300 adults are affected by advanced sleep phase. The circadian rhythms for these “extreme early birds” operate ahead of the average schedule. They fall asleep before 8:30 p.m. and rise before 5:30 a.m. without help from stimulants, sedatives, or bright lights to mimic daylight.

Why Oversleeping Can Be Problematic 


When it comes to sleep and health, think of it as a U-shaped correlation. While that middle is what most of us aim for, it’s the two ends — a lack of sleep and too much sleep — that have been linked to chronic diseases and mental health impacts. If you often need more than 9 hours of sleep to feel your best, the reasoning could be anything from grinding your teeth at night or sleep apnea to an underlying health issue. Oversleeping has also been found to lead to chronic issues down the line, like diabetes or heart disease.

How To Find The Right Amount of Sleep For You 

As fundamental as it is to our health, sleep is anything but straightforward. There are alarms, coffee, and social media scrolling that can disrupt our sleep cycles, not to mention the fact that sleep needs change as you age. Newborns need more sleep than older adults, for example, and hormonal shifts during pregnancy can impact sleep quality. 

With those variables in mind, ultimately, how much sleep we need is less about fitting the mold and more about listening to your internal clock. Ask yourself how rested you feel after you wake up, whether you rely on caffeine to keep you going, and if you feel drowsy during the day. It may take a little trial and error, but keeping track of those patterns can help you find your sweet spot.

The Bottom Line

Similar to diet and exercise, sleep is an essential part of head-to-toe health. And just like those pillars, it boils down to finding the routine that works best with your body. Whether you need lights out by 9 p.m. or thrive on 6 hours of sleep, pay attention to the physical and mental effects. With some mindfulness, you’ll be able to determine just how many zzz’s you need. And if you need some support to perfect your sleep routine, check out our 20 life-changing sleep hacks.