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How Much Sleep Do You Need? 8 Hours Isn’t for Everyone

Habits

sleep

I’ve been particularly looking forward to the sleep chapter in John Medina’s book Brain Rules (one of my current reading books) because I was interested to know once and for all how much sleep I needed. Was 8 hours really the magic number? What were the consequences of averaging, say, 7 hours, or 6? What about naps? I was interested in knowing how sleep affects our brains so that I could begin to see how it might affect self-motivation.

The answers were very helpful in some ways and completely unhelpful in others. What are the findings about how much sleep we need? Research so far seems to say that there is no definite number, and sleep needed varies widely from person to person. Some people (who have a condition called “healthy insomnia”) only need 4 or 5 hours a night and don’t seem to suffer any ill effects. Kids going through puberty definitely need more, preferably in the morning. There also seem to be genes that determine whether someone is a morning person (a “lark”), a night owl, or (like most of us) a “hummingbird,” which is to say someone with a “normal” sleep schedule. Sleep needs and daily schedules change as a person ages, too.

Too little sleep has serious costs
But one very clear finding across the board is that not getting enough sleep actively sabotages the brain’s abilities. As Medina puts it, “Sleep loss hurts attention, executive function, immediate memory, working memory, mood, quantitative skills, logical reasoning ability, general math knowledge … manual dexterity … and even gross motor movements.” Also, interrupted sleep or inadequate sleep severely limits our ability to remember things we learned that day, increases stress, and causes effects that mimic accelerated aging. Not getting enough sleep even forces the body to crave sugar while reducing our ability to make good use of sugar when we get it, playing havoc with healthy eating.

Figuring out your own sleep needs
Most of us already knew that shorting ourselves on sleep was bad (though maybe we didn’t realize it was that bad). But how do we figure out how much sleep do we actually need to not condemn ourselves to tired, inattentive, grumpy days? The best answer I can give is that we probably already know. If you wake up feeling overtired, it’s probably no secret to you that you could use more sleep. Some of us treat sleep as expendable if something else important is going on, but since even small sleep shortages can have a major impact on performance, we may be more effective if we get the right amount of sleep even though that takes away from the waking hours in which we can actually get things done. If you find yourself adding in extra “down time” during the day because you’re tired, or making mistakes, being distracted, or having trouble getting things done because of a sleep debt, then the “bonus time” you’re getting by cutting out sleep–and possibly more time besides–may be getting used up by the problems caused by not getting enough sleep. In other words, shorting ourselves on sleep is both unpleasant and unproductive.

The need for naps is built into our genetic code
Pretty much everyone, it turns out, is programmed to need about a half-hour nap in the early afternoon, although some of us need it more than others. This isn’t just an artifact of not getting enough sleep at night: it’s a normal part of the sleep-wake cycle in human beings. Many of us won’t have the option of getting this extra sleep on a regular basis, but it may be worth experimenting with it when you do have the freedom to try and seeing if it doesn’t give you a lot more energy and attention. In one study, pilots who took a 26-minute afternoon step performed 34% better than pilots who didn’t. That’s a big improvement!

At the very least, it’s best not to schedule things that require a lot of attention in the early afternoon if you can help it.

Sleep and self-motivation
How does this affect self-motivation? Pretty profoundly, it turns out. Self-motivation requires knowing what you need to do, paying attention to your priorities, devoting a little time and focus to moving forward, being self-aware, and solving problems that come up with your process. All of those things are compromised when we short ourselves even an hour or two of sleep a night. So with enough sleep, self-motivation will tend to get noticeably easier.

I know you will have gotten the advice to “get plenty of sleep” time and time again, and if you aren’t currently getting enough, it might be because you are trying to get enough time in the day to accomplish everything that’s important to you. Only you can judge whether or not a little sleep-deprivation is worth being less intelligent and less capable while the sleep debt lasts. In the past, at least, I’ve often gone with a little sleep deprivation in the service of what sometimes seems like a good cause. Put in this light, though, I’m not sure I want to continue to make that kind of a bargain. I’m beginning to think of it this way: if I can accomplish everything I already accomplish without always getting enough sleep, how much better could I do if I were actually operating at full capacity? It’ll be worth finding out.

earplugs

By the way, if noise interferes with your sleep, or if you just want a little more silence in your life, you might want to try any brand of soft, foam earplugs with rounded ends (above). I’ve found these very helpful, especially for sleeping when someone else has to get up early, during travel, working while someone’s watching a TV or listening to music nearby, concentrating while my neighbor is mowing the lawn, etc. I haven’t been as happy with plastic earplugs or with the kind that are made of harder foam and don’t have a rounded end. Fortunately, the earplugs don’t block out sound completely, so it’s still possible to hear (faintly) a phone ringing or an alarm going off even while wearing them.

Photo by tempophage

2 Comments

2 Comments

  1. Robin Dickinson  •  Sep 12, 2009 @1:46 am

    Hey Luc,

    thorough, and evidence-based – just how I like it. It’s very useful to know that the need for naps is built into our genetic code. I’m going to implement early afternoon naps this coming week and look forward to productivity gains.

    Good job.

    Robin

  2. Luc  •  Sep 12, 2009 @12:50 pm

    Hi Robin,

    The naps thing surprised me, too. I don’t have many opportunities to actually try it out, but I may today, and the experiments so far have definitely been promising. I’d love to hear whether it makes a meaningful impact for you or not.

    Thanks too, by the way, for the encouragement on the site; it’s much appreciated.

    Luc

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