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The importance of sleep: It’s not just how much, but when

“The first thing is to know yourself and to know your own biological clock,” says Dr. Michael Howell, a U of M assistant professor of neurology and medical director of the Fairview Sleep Centers in Edina.

U.S. Centers for Disease Control and Prevention (CDC) has declared insufficient sleep a public health epidemic.

First of two articles

Sleep is crucial for good mental and physical health, yet it’s often downplayed or even overlooked in discussions about what individuals — and society — can do to improve people’s health.

Survey after survey has found that Americans get either too little sleep or sleep that is of very poor quality. In fact, within any 24-hour period, a third of Americans report having not received the recommended minimum of seven hours of sleep. 

As I’ve noted here many times before, lack of sleep is associated with an increased risk of several chronic diseases, including type 2 diabetes, heart disease and depression. And it’s also cited as a major contributor to traffic accidents, as well as to industrial accidents and medical errors.

No wonder the U.S. Centers for Disease Control and Prevention (CDC) has declared insufficient sleep a public health epidemic.

Recently, I discussed the importance of sleep with Dr. Michael Howell, an assistant professor of neurology at the University of Minnesota, program director of the Clinical Sleep Medicine Fellowship at the Hennepin County Medical Center and medical director of the Fairview Sleep Centers in Edina. An edited version of Part 1 of that discussion follows. Part 2 of the interview will appear in Second Opinion tomorrow.

MinnPost: I often think of getting enough sleep as one of the three legs of the “three-legged stool” of daily habits that people need to persist with in order to be healthy. The other legs are, of course, regular exercise and a healthful diet. But most of the time, health advice focuses just on exercise and diet.

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Dr. Michael Howell: Let me expand on that idea. A medical student asked me the other day about going into emergency medicine [a field of medicine that typically requires working night shifts]. He wanted to know what would happen if his sleep was bad for a while. Would it cause him any problems? Would it curtail his life? Unfortunately, the answer is yes. … But nobody would say, “You know what. I’ve really eaten well all my life. I take good care of myself, but for the next four years, I’m going to eat crap. Is that going to be a problem?” Of course it’s going to be a problem.

MP: So good sleep habits, like ones for exercise and diet, need to be practiced over the long term.

MH: Yes. And becoming a good sleeper takes practice — above and beyond getting treatment for a sleep disorder, such as sleep apnea or restless leg syndrome. My favorite phrase is “It’s not the volume, it’s the time.” In other words, it’s not just the amount of sleep you need, but when you get it. One of the real challenges with exogenous [artificial] light in the evening is not that it’s keeping us awake. The problem is that it’s delaying our entire body clock, our circadian biological rhythm.

Let’s take a typical example from a group of medical students I was talking to recently. I asked them what time would be ideal for them to fall asleep, and they essentially came up with about 1 in the morning. They also said they would ideally like to sleep until 9 or 10 in the morning. But of course, they have to do morning hospital rounds, which means they have to try to go to bed around 10 or 11 at night so that they can wake up at 6. Sometimes that works. Sometimes it doesn’t. [But even when it works] eight hours of poorly timed sleep is not particularly satisfying, and, in and of itself, can lead to feelings of grogginess, mood issues, alertness issues, motor vehicle accidents — those sorts of things.

MP: But modern society is structured to make it almost impossible for people to time their sleep in the way that’s healthiest for them. So what can individuals do? 

Dr. Michael Howell
Dr. Michael Howell

MH:  The first thing is to “know thyself.” Many people who come to me for treatment with a circadian rhythm delay are convinced that they have insomnia. But having insomnia is very different from being somebody who, if the world would let you, could fall asleep at 2 or 3 in the morning and sleep until noon and be just fine.

So the first thing is to know yourself and to know your own biological clock. When would you sleep if there was no work, no bed partners, no pets, and nobody waking you up — if you could just go to bed when you felt like it and wake up when you were done sleeping? What would that look like? All of us have a natural sleep window when sleep works best for us. Even if you’ll never be able to sleep within that window, it’s a good idea to have at least some concept of when it is.

MP: And for some people that window is a very early one.

MH: Yes. Some people can barely keep their eyes open at 7 or 8 at night. They’ll try to stay awake until 9 or 10, but then, at around 2 or 3 in the morning, they’ll wake up and not be able to sleep any later. That’s an advanced circadian rhythm. It’s a particular problem for older people, for our circadian rhythms start advancing with age.

MP: What should people do once they recognize the pattern of their circadian sleep rhythm? 

MH:  If your problem is circadian rhythm delay [difficulty falling asleep and waking up “early”] and there’s no way you can change your lifestyle to facilitate sleeping in until 9 or 10 in the morning, my advice is to stop trying to fall asleep at night. Instead, focus on what you’re doing in the morning. Excessive [artificial] light in the evening is [part of the problem]; however, there’s a flip side that a lot of people miss. We’re not only getting too much light in the evening, we’re also not getting enough light in the morning. A lot of us stumble around in the dark in the morning, and the only sunlight we get is when we’re squinting through our windshields on the way into work. That doesn’t really count. You need a good 30 to 120 minutes of sunlight in the morning. If you can’t get that, then use a light box, like the ones people use to treat seasonal affective disorder. That will help cue your body that a new day has started.

The other thing you can do is take a low does of melatonin — about one-half to one milligram at most daily. You need to take it about four to six hours before you would like to go to bed. That’s the hard part because most people think of melatonin as a kind of alternative sleeping pill, which is exactly the wrong way to think about it. It’s not a sleeping pill. It’s a circadian compound that essentially triggers your brain to think the sun has gone down. [If you want to get up at 6 in the morning], then you are going to be using melatonin around 6 in the evening. What you’re doing is giving yourself a sunset [the taking of the melatonin] and a sunrise. Make this your new ritual, and you can move your circadian cycle earlier and kind of align it more appropriately. 

MP: What about people with advanced circadian cycles?

MH:  Especially as we get older, it tends to be a little bit more socially accepted that we go to bed earlier and wake up earlier. But then, if you have a wedding or something for which you have to stay up late, it can be quite challenging. What you can do — and, in general, it tends not to work as well as sunlight in the morning does for the circadian-delayed crowd — is to get a light box and blast yourself with light in the evening. That may help push your circadian rhythm back.

MP: These practices can help, but they’re not going to “cure” either advanced or delayed circadian sleep rhythms, correct?

MH: I usually warn people — the night owls — that when they start using [the light box/melatonin therapy], they’re not going to like it. It will feel “wrong,” like they’re on permanent jet lag. But I also tell them that it’s an example of how a medicine has to taste bad to work. It’s a sign that it’s actually shifting your circadian rhythm.

MP: How long does the adjustment take?

MH:  It varies. But most people usually notice a difference within a few weeks. 

MP: But it’s not permanent.

MH: No. People can get into the [new] routine, but then, after a long weekend or a week of vacation, they’re right back where they started. Because, again, [our circadian sleep cycle] is a natural genetic tendency. It’s built into our DNA.