Is 5 Hours of Sleep Enough?

You meant to be asleep by eleven. You were in bed by eleven. The lights, somehow, didn’t go off until closer to one. By the time the alarm goes, you’ve had about five hours.

For a lot of us, five hours has become the default. We mean to switch off the phone. We mean to put down the book. Somehow it’s 1 am, the alarm is set for six, and we’re staring at the ceiling, promising tomorrow will be different.

But is five hours actually enough to get you through the day? Or is it slowly catching up with you? We asked our sleep expert, Sammy Margo, and pulled apart our 2026 Sleep Survey to find out.

The short answer: more than five hours.

According to the NHS, most adults need between seven and nine hours a night for the body to repair, the brain to file away memories and the immune system to do its job properly.

Here’s how Sammy Margo, our sleep expert, puts it:

“Most adults need between 7 to 9 hours of sleep per night to function at their best. The exact number can vary depending on the individual, but the goal is to wake up feeling refreshed and alert. Consistently getting the right amount of sleep is crucial for your overall health, so try to make it a priority each night.”

Sammy Margo, Dreams’ Sleep Expert

The exact figure varies slightly depending on age. Teenagers tend to need eight to ten hours. Younger children need nine to thirteen. Older adults still benefit from a solid seven, even if their sleep starts to feel lighter and more broken.

For most adults, no. Five hours sits well below what every major sleep authority (the NHS, the Sleep Foundation, the American Academy of Sleep Medicine) considers a healthy minimum. Anything under seven hours regularly is generally considered insufficient sleep for most adults.

A study published in PubMed Central® followed more than a million adults over six years. Those who slept 6 or 7 hours a night had a lower mortality rate than those who regularly slept 8 or more hours, or less than 4.

There’s also a difference between coping and getting good quality sleep. You can survive on five hours. Most of us have, after a newborn, a deadline or a party. Survival is one thing. The body actually working at its best is another.

After just five hours of sleep, you can expect:

• Slower reaction times: The AAA Foundation for Traffic Safety found that drivers who reported sleeping 4-5 hours per day had a 5.4 times higher crash rate than drivers who usually sleep 7 hours or more per day.
• A grumpier mood: The brain’s emotional centre (the amygdala) can get jumpier when sleep is short, which is why everything can feel louder or more irritating the day after a bad night.
• Foggy thinking: Memory, focus and decision-making all dip, according to the Sleep Foundation.
• Hungrier the next day: Sleep loss can raise ghrelin (the hunger hormone) and lower leptin (the fullness hormone), so you may reach for the biscuit tin more than usual.
• A bigger sweet tooth: Studies show short-sleepers crave more sugar and refined carbs.

Our 2026 Sleep Survey of 2,000 UK adults backs this up. When people don’t sleep well, here’s what they say happens the next day:

• Low energy: 54%
• Fatigue: 51%
• Low mood: 39%
• Irritability: 35%
• Poor concentration: 34%
• Need to nap: 28%
• Reduced productivity: 28%
• Headaches: 27%
• Increased hunger: 15%

Not the morning any of us are hoping for. A poor night can colour an entire day, from the patience you have for the people around you to the patience you have for yourself. Most of us know the feeling, even if we don’t always link it back to the hours we missed.

Worryingly common. According to our Sleep Survey, the average Brit sleeps 6.4 hours a night. That’s already below the recommended minimum. Look closer, and the picture gets harder to ignore:

• 44% of UK adults sleep just 5 to 6 hours a night
• 8% get only 3 to 4 hours
• 1% manage 0 to 2 hours
• Only 41% sleep the recommended 7 to 8 hours

In other words, more than half of British adults are running on less sleep than their bodies need.

Quality matters as much as quantity, and a lot of us are losing on both fronts. We surveyed 2,000 people, and 19% told us they have a disturbed, broken or bad night’s sleep every single night of the week. The average is 3.4 bad nights a week.

You probably know someone who swears they only need five hours and breezes through the day. A very small slice of the population (estimates suggest under 1%) carries a genetic mutation linked to short sleep. These so-called “short sleepers” wake up feeling refreshed after 4 to 6 hours and don’t seem to suffer the usual consequences. Researchers at the University of California, San Francisco, have identified specific genes (DEC2, ADRB1, NPSR1) that seem to allow it.

For everyone else, five hours feels okay until it doesn’t. The body adapts to running on less, but adaptation isn’t the same as health. We’ve written more about this oddity in who are short sleepers and why don’t they need sleep.

Sleep is now considered one of the most important things you can do for your heart. The American Heart Association added sleep duration to its “Life’s Essential 8” health behaviours in 2022, alongside diet, exercise and not smoking. They recommend 7 to 9 hours of sleep a night for adults to keep the heart and the rest of the body in good shape.

When you regularly miss out on sleep (less than seven hours a night), the knock-on effects show up across the body, from your heart to your hormones to your immune system. Studies show some of the common effects include:

• Obesity in adults and children
• Diabetes and impaired glucose tolerance
• Cardiovascular disease and hypertension
• Anxiety symptoms
• Depressed mood
• Alcohol use

One short night here and there is nothing to worry about. Most of us have them, and our bodies bounce back. It’s the steady drip of five-hour nights, week after week, that slowly catches up with you.

Forget the numbers for a second. The body usually tells you. Ask yourself:

1. Do you wake up before your alarm most mornings, or do you hit snooze five times?
2. Do you need caffeine to feel human before noon?
3. Are you nodding off in meetings, on the sofa, in the car as a passenger?
4. Do you crash at the weekend and sleep two extra hours?
5. Are you generally in a flat mood for no obvious reason?

If you’ve answered yes to most of these, your body is probably running on fumes. In our Sleep Survey, only 5% of UK adults said they always wake up feeling refreshed. About 30% said they rarely or never do. The bar has slipped a long way.

Sleep responds well to small, repeatable changes. You don’t need a five-step morning routine. Start with some of the basics:

• Pick a bedtime and stick to it, even at weekends
• Get ten minutes of sunlight outside before 10 am
• Keep your bedroom cool, around 15.6 to 18.3°C
• Skip caffeine after midday (it has a five-hour half-life)
• Brain-dump your worries in a notebook before bed, or try the 4-7-8 breathing method
• Check your mattress – a worn-out one can wreck a night. Our Sleepmatch tool finds the right level of support for you in a few minutes

For more detailed advice take a look at our guide on ways to sleep better at night.

Five hours may get you through the day. It won’t get you through it well, though. If five hours has quietly become your normal, your body is keeping a tally somewhere, even if you haven’t noticed yet. The fix doesn’t have to be dramatic. An earlier bedtime, a cooler room, a phone left in another room. Small changes, repeated.