Why I Sleep 8 Hours Every Night

I was Chief of Staff at Food Pharmer and on the founding team at Only What's Needed. My work has been about what goes on our plates.

The habit I protect hardest has nothing to do with food. I sleep from 11pm to 7am, a full 8 hours, and I've done it since school.

Around me, 5 or 6 hours is normal. People say it with a kind of pride, like it proves how hard they work.

Those 8 hours are the smartest thing I do for my work and body.

Here's why, and here's what the research actually says.

How much sleep an adult needs

The American Academy of Sleep Medicine and the Sleep Research Society looked at the evidence together. Their joint advice is plain.

Adults should sleep 7 hours or more a night, on a regular basis.

Their report links regularly sleeping less to weight gain, diabetes and high blood pressure. Heart disease, depression, mistakes and accidents are on that list too.

7 hours is the floor in that advice. I aim for 8 because I want room for a bad night.

Short sleep makes you worse at your job, and you can't feel it

This is the study that changed how I think about sleep.

In 2003, a lab kept healthy adults on a fixed amount of sleep for 2 weeks. One group got 6 hours in bed a night.

By the end, that group did as badly on tests as people kept awake for a full night. Their attention and working memory slipped almost every day.

Their own sleepiness ratings barely rose after the first few days.

They felt only a little tired, while their scores kept falling.

A group on 4 hours did worse still, matching 2 full nights awake.

So when someone tells me they're fine on 5 hours, I believe they feel fine. The research says feeling fine is a poor guide.

Short sleep makes you hungrier

In a 2004 study, young men slept only 4 hours a night for 2 nights. The same men also had 2 nights of 10 hours, for comparison.

After the short nights, their hunger went up by 24%, almost a quarter. The hormone that signals fullness dropped, and the one that drives hunger rose.

Their cravings rose most for sweet, salty and starchy food.

I've read food labels for work, so this one matters to me. When you are tired, you reach for exactly the packs I warn people about.

Short sleep may change what a diet takes off your body

This study looked at what happens to a diet when sleep is cut short.

In 2010, 10 overweight adults ate a reduced diet for 2 weeks, twice. One round they had 8.5 hours in bed each night, and one round 5.5 hours.

They lost about the same weight both times, but what they lost was very different.

• On short sleep, the fat they lost fell by 55%, so less than half as much.
• The loss of lean tissue, like muscle, went up by 60%.

Both rounds had the same diet and showed the same drop on the scale. The difference was in what that weight was made of.

It's a small study, and it only ran 2 weeks. Treat it as a signal, not proof.

Keeping the same hours may matter as much as the total

A 2024 study tracked sleep for about 60,000 people in the UK with wrist devices.

In that study, more regular sleep was linked to a lower risk of dying over the follow-up. Keeping the same hours predicted that risk better than total hours did.

The authors suggest a simple target: fall asleep and wake up within about a 1-hour window every day.

This is the part of my habit I'd defend most. 11 to 7 is the same on a Monday and a Saturday, give or take.

Some people really can live on less

I want to be fair here. A few people carry rare gene changes that let them do fine on about 6 hours.

The first one was found in 2009, in a single family. It's rare, and most of what we know comes from a handful of families.

If you need 2 coffees to get going, you're probably not one of them.

What I actually do

3 habits keep my 11 to 7 steady:

• The same bedtime and wake time, weekends included
• Daylight on my face soon after I wake
• A dark bedroom, with the curtains fully shut

The research backs all 3.

• The 2024 study's authors suggest keeping sleep and wake times inside about a 1-hour window.
• Light is the body clock's main signal, and experts say daylight is the best daytime source.
• The same experts say the bedroom should be as dark as possible while you sleep.

One more habit is worth trying, and it's about the lit screen before bed.

In one study, a lit tablet before bed delayed the sleep hormone by over 1.5 hours. That study compared a lit tablet with a printed book, in the same dim room. Tablet readers took longer to fall asleep and felt less alert the next morning.

One more rule worth stealing

Watch the time of your last coffee.

In a 2013 study, people took a big dose of caffeine 6 hours before bed. The dose was about 2 or 3 regular coffees.

It still cut their sleep by more than 1 hour on a home sleep monitor.

For an 11pm bedtime, 6 hours back is 5pm. That's the latest coffee this study supports.

Why this belongs next to food

Most of my work has been about labels, sugar and salt. Sleep turned out to matter just as much, and it has no label at all.

It costs nothing and it's boring to talk about. Research links it to your hunger, your focus and what a diet takes off your body.

If you try one thing, fix your wake-up time for 2 weeks. Keep it inside a 1-hour window, weekends too.

Are you a 5-hour sleeper or an 8-hour sleeper right now?

Sources

Every number above comes from one of these.

• Watson NF et al, Recommended amount of sleep for a healthy adult, joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society, Sleep 2015, 38(6), 843-844, doi 10.5665/sleep.4716
• Van Dongen HPA, Maislin G, Mullington JM, Dinges DF, The cumulative cost of additional wakefulness, Sleep 2003, 26(2), 117-126, doi 10.1093/sleep/26.2.117
• Spiegel K, Tasali E, Penev P, Van Cauter E, Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite, Annals of Internal Medicine 2004, 141(11), 846-850, doi 10.7326/0003-4819-141-11-200412070-00008
• Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD, Insufficient sleep undermines dietary efforts to reduce adiposity, Annals of Internal Medicine 2010, 153(7), 435-441, doi 10.7326/0003-4819-153-7-201010050-00006
• Windred DP et al, Sleep regularity is a stronger predictor of mortality risk than sleep duration, Sleep 2024, 47(1), zsad253, doi 10.1093/sleep/zsad253
• He Y et al, The transcriptional repressor DEC2 regulates sleep length in mammals, Science 2009, 325(5942), 866-870, doi 10.1126/science.1174443
• Brown TM et al, Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults, PLOS Biology 2022, 20(3), e3001571, doi 10.1371/journal.pbio.3001571
• Chang AM, Aeschbach D, Duffy JF, Czeisler CA, Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness, PNAS 2015, 112(4), 1232-1237, doi 10.1073/pnas.1418490112
• Drake C, Roehrs T, Shambroom J, Roth T, Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed, Journal of Clinical Sleep Medicine 2013, 9(11), 1195-1200, doi 10.5664/jcsm.3170