How much did you sleep last night?
If the answer is "about six hours, and I feel fine," you're in good company. Plenty of busy people run on six and swear it works for them.
The tricky part is that last bit. I feel fine. One of the best known sleep studies suggests that feeling might not be telling you the whole truth.
The Study That Changed How Researchers Think
In 2003, a team at the University of Pennsylvania led by Hans Van Dongen and David Dinges published a study in the journal Sleep. They limited healthy adults to 4, 6 or 8 hours in bed per night for two weeks and tested them every day.
The 8 hour group stayed sharp. The other two groups didn't.
People on 6 hours a night got steadily worse on attention tests over the two weeks. By the end, their performance had dropped to a level similar to people who had gone a full night or more with no sleep at all.
The Part Nobody Notices
This is the finding that really sticks with me.
The people sleeping 6 hours didn't feel that bad. Their sleepiness ratings rose a little at first, then mostly leveled off. Meanwhile, their test scores kept sliding.
In plain words, they got used to feeling tired long before their brains got used to being tired. So "I feel fine on six hours" might be true. It just might not mean you're performing fine.
How Much Sleep Do Adults Actually Need?
The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults get 7 or more hours of sleep a night on a regular basis.
A small number of people do seem to need less. But they're rare, and most of us aren't in that group, no matter how much coffee we drink (and I say that with love for coffee).
Easy Ways to Get Better Sleep
You don't need a perfect routine. A few steady habits go a long way.
- Keep the same wake time. Even on weekends, as much as you can. A steady wake time is one of the strongest signals for your body clock.
- Get daylight in the morning. A few minutes outside after waking helps set your internal clock.
- Cut caffeine by early afternoon. It can stay in your system for hours.
- Make the bedroom dark, cool and quiet. Simple changes like blackout curtains help more than you'd think.
- Give yourself a wind down. 20 to 30 minutes of something calm before bed. Reading, stretching, a warm shower.
- Keep the phone out of reach. If it's on the nightstand, it's too easy to grab "for one minute."
Note: if you snore loudly, wake up gasping or feel exhausted even after a full night in bed, talk to a doctor. Sleep problems like sleep apnea are common and very treatable.
Protect Your Sleep Like It Matters
Sleep is easy to cut when life gets busy. It doesn't send an angry email when you skip it.
But clear thinking, good moods and good decisions all lean on it. Try adding just 30 minutes a night for two weeks. You might be surprised how much sharper "fine" can feel.
