How Much Sleep Do You Actually Need?

Everyone says you need 7 to 9 hours of sleep. But here’s the honest truth: that advice is outdated. Sleep researcher Merijn van de Laar has a reassuring message — most people sleep just fine. We’ve simply worked ourselves into a panic about it.

How many hours of sleep do you really need?

About 7 hours. Large-scale population studies show almost everyone sleeps between 6 and 8 hours, with the healthiest range (for both brain function and longevity) around 7. The widely repeated “7 to 9 hours” rule is outdated — it comes from older research and the false assumption that everyone was chronically sleep-deprived. They weren’t. We sleep worse than we used to, but not less.

Here’s what actually matters: your sleep need is personal. Van de Laar compares it to calories. “We don’t say someone needs 1500 to 4000 calories — that tells you nothing.” Want to find your real sleep need? Look at the second week of your holiday, when life settles down. Note what time you naturally feel sleepy and wake up. That’s your baseline.

“I function fine on 5.5 hours” — really?

Many people are convinced they can get by on very little sleep. Van de Laar pushes back hard here: people who genuinely need 7.5 hours but chronically give themselves 5.5 consistently score worse in research on focus, planning, and organisation — even if they don’t notice it themselves. He compares it to drunk driving: “Even drunk drivers think they’re fine. Sleep deprivation works the same way.”

Waking up in the night is completely normal

Wake up two or three times a night? No problem, says Van de Laar. Waking a few times is entirely normal, and lying awake for up to about 20% of your time in bed falls within normal variation. There’s no evidence that brief awakenings harm your health on their own.

The problem, he argues, lives between our ears. “We’ve romanticised sleep too much,” he says. The idea that good sleep means passing out in five minutes and sleeping solidly for seven hours straight simply doesn’t match reality.

The sleep stages: why deep sleep matters

Over a night, you cycle through four distinct stages, each doing different work. Deep sleep is when your body repairs itself — tissues and muscles grow, your brain essentially gets cleaned. Light sleep helps you consolidate simple skills, and REM sleep matters for creativity and processing emotions and memories. The good news: most of your deep sleep happens in the first 4.5 to 5 hours, so you usually get enough even with a shorter night.

What actually works for poor sleep?

If you’re genuinely struggling to sleep, there’s a proven fix. The most effective treatment for insomnia is sleep restriction — you deliberately spend less time in bed. This builds up “sleep pressure” (a chemical called adenosine), making it easier to fall and stay asleep. Between 50 and 80% of people sleep noticeably better within weeks. Once it improves, you gradually extend your time in bed by about 15 minutes per week.

Beyond that, strength training helps: more muscle mass burns more energy and builds additional sleep pressure. Don’t expect miracles, though — exercise typically adds around 11 to 12 minutes of sleep for people who weren’t exercising before.

And screens? The panic is overblown. Recent research shows phone light is actually quite dim. What matters more is what you’re doing: watching a relaxing show is fine; doom-scrolling or work emails keep you wired.

What about magnesium and other supplements?

Pills and gadgets are, at best, the cherry on top, says Van de Laar. The real gains come from acceptance, realistic expectations, and letting go. That said, magnesium may help with relaxation and muscle recovery, and it’s one of the most popular supplements for sleep. If you try it, go for an absorbable form like magnesium bisglycinate.