Dr. Posner on Tips for Better Sleep

Sh*t you should know by now: The Sleep Edition

If you, too, were once the weird kid awake first at the slumber party, hanging out in the kitchen prepping breakfast with the ‘rents, then you might agree that sleep has always been somewhat elusive. We’d go so far as to say we remember our few great sleeps the way one would recall a great meal or a fine wine. Determined to put an end to angsty bedtimes, one of us decided to work it all out with a sleep therapist and, with a lot of learning, nighttime drama is now a distant dream. We’re not hogging the covers—we tapped our sleep sensei Dr. Donn Posner to share with our readers what we’ve all been missing about getting our zzzs.

So eight hours, is that a thing?

It's not a thing. That number is out there, but saying everybody needs eight hours is like saying everybody needs to be six feet tall, because that's, say, the average for men. While there is no right number for everyone, there is a right number for each individual. And I think most people don't have any clue what their right number is. The American Academy of Sleep Medicine and the National Sleep Foundation would now say that a better life happens in between seven and nine hours. So eight's smack in the middle of that. But even that is a bit problematic because there are going to be people outside those standard deviations, and the epidemiological research is not done in a way to clearly say what happens to people who only get six hours, but feel fine—and we know they’re out there. I don't know what those data would look like, but my suspicion is people who get 6 hours and feel perfect, can still live long healthy lives.  The problem is when people are getting less than they need and do not feel fine. And it is likely true that many of us could use more? I do think people get, say, six and a half hours and feel okay, but they're not necessarily at their best. 

When we define the right amount of sleep, we define it in a 24 hour way. So it's not just the amount of sleep you're getting, but it's the amount of sleep you're getting and how does that leave you feeling the next day? And if you function well, if you have energy, if you're not falling asleep, if you concentrate well, then you're likely getting at least close to what you need. So I always encourage people to try to learn or figure out what their best sleep need is so that they can optimize their performance. If they do that, they might find that getting this amount of sleep really makes them feel a way that they didn't know they could feel.

On that point, sleep trackers: yay or nay? How can we better think about whether we’re getting enough sleep or what our number might be?

There are a number of sleep trackers on the market, everything from wearables to mattress pads. I don't want to endorse any of the products; some are a bit better at saying, this was your total amount of sleep. But the notion that they're good at predicting how much deep sleep you got and how much light sleep and how much REM sleep—that's much more of a crapshoot. When you really look at the research, it doesn't tend to hold up against gold standards.

I think the trackers can be useful for good sleepers to expand and optimize their sleep. The National Sleep Foundation would say that even good sleepers may not be getting the most out of their sleep. So they could utilize a wearable to try to find less variability around the mean. If they’re averaging seven hours of sleep because some days they get five and some days they get eight and a half, they’re going to be better served trying to move to seven every day, or close to every day, than up and down. They could take that data and then say, well, is it reasonable for me to try to go to bed a little earlier, to get a little bit more sleep? And I would do it gradually, to see if I can increase the amount of sleep I'm getting, and how does that relate to how I feel I'm functioning during the day?

This is totally separate from people with insomnia. I think they should put these wearables down, because by and large, they just make people with insomnia more nervous and that influences their sleep in a negative direction.

What is the difference between acute insomnia and chronic insomnia? We all casually toss off ‘I'm an insomniac,’ or ‘I had insomnia last night,’ but what does it really mean?

Let's start at the more extreme end, which is chronic insomnia or insomnia disorder. That's trouble either getting to sleep, maintaining sleep, or waking too early, for more than three nights a week, for more than three months. So three months is sort of the chronicity cut off point for chronic insomnia. And it has to be associated with daytime symptoms. There has to be some detriment that you attribute to the sleep loss.

If you have a big hour hole in the middle of your night, and then as a result of that, you say I'm more fatigued or irritable, that's insomnia. But again, there are people who are going to be short sleepers, who are outside of those standard deviations.

Then we can back off of that and say, okay, so what about acute insomnia? Acute insomnia is anything short of that, meeting those same definitions, but less than three months. We don't even really count a night as acute insomnia—everybody on the planet has a bad night from time to time. But anything from about three nights to three months would be considered a bout of acute insomnia. It is reasonable enough to think that whatever the stressor is that is causing you to sleep poorly in the short term, when it resolves, the insomnia will resolve as well. However, for people with chronic insomnia this is not always the case. The stressor is resolved but the insomnia goes on and then people are at a loss to know what to do.

What are some of the biggest misconceptions about good sleep?

The first we've already dealt with, which is that everybody needs eight hours. I think another misconception is that somehow REM sleep is somehow the deepest best stage of sleep. The truth is all of the stages serve a function and are important, REM included.  .

REM sleep is not a particularly deep level of sleep. During REM we are dreaming, heart rate is variable, blood pressure is up, and the measured brain wave activity looks more like a very light stage of sleep. The deepest sleep is stage 3 sleep and most of that is done by the first half of the night. Also, I’ve had some patients tell me that they worry that when they can’t remember any dreams that they must not have had any REM sleep. In almost all cases this would not be true. If you are dreaming and wake right out of REM sleep you will likely remember your dream. However, if you are dreaming for a bit in REM sleep and then shift to stage 2 sleep and later wake from stage 2 you won’t remember your dream. This does not mean that you did not have REM.

You know how many people there are out there who say, ‘Oh my God, I just, I can't even start my day without a cup of coffee. I wouldn't even know how to wake up.’ So tell us about caffeine.

One of the major factors in good sleep is what we call sleep drive, which creates an increasing sleepiness pressure over the course of the day. If you're awake, you're building sleep pressure. One of the internal mechanisms of that is a buildup of a byproduct in your brain called adenosine, which makes us sleepy. Caffeine adheres to adenosine receptors. So when we talk about chemicals and receptors, we're talking about lock and key. It's like saying that caffeine shoves itself into the lock, and therefore adenosine can't open that lock.

The thing is, if you're a good sleeper, chances are you've diminished all the adenosine in your brain over the course of the night. That’s one of the benefits of sleep, to wash this waste product from the brain. So the question is, what is caffeine doing if there's no adenosine to block? I think people can tell themselves that it's waking them. A lot of us wake in the morning with a little bit of what we call sleep inertia. You can be the best sleeper in the world, and you can still wake up in the morning feeling like you're not quite there yet. You need to wipe the cobwebs out of your eyes and get moving a bit. That can take anywhere from five to 30 minutes in a good sleeper. By the time some of that is done, you're having your coffee, so it coincidentally coincides with the time when your sleeping inertia is wearing off. So yes, in fact, you might feel better, but it's also possible you might feel better even if you didn't have the coffee.

Now, a cup of coffee can still be a nice warm hug in the morning for any of us. And if people really drink a lot of coffee, they can have physical symptoms from withdrawing from the caffeine. So I'm not telling everybody to throw their caffeine out. Also, if you're not a good sleeper, it's possible that you are waking up in the morning with still too much adenosine on board because you haven't slept enough, in which case caffeine would be useful under those circumstances.

Everyone's focused on blue light and blue light glasses. We know we all look at screens a lot. What is your feeling about those?

One of the major factors of sleep is the circadian rhythm. It’s responsible for many bodily functions, including a sleep-wake cycle. That circadian rhythm is regulated hormonally and genetically, but very much influenced and entrained by a number of factors, the biggest of which is light exposure. It turns out that the wavelength of light that seems to have the most profound effect on circadian rhythm is blue light, which is why everybody's hearing this stuff about blue light. It's not that it’s bad. In fact, blue light is useful to wake you at certain times of the day. So in the evening, if people want to download blue light filters on their laptops or phones that's all fine. It's not a bad thing to do. If they don't really have a lot of circadian disturbance, it's not that big of a deal one way or the other, but if they want to be cautious, they can certainly download blue light filters. But only at night.

I do get concerned because now you see people hawking eyewear, even prescription glasses, and saying, "Oh, you can just get this in blue light filters." The idea that we can just cut out blue light all day long is not necessarily a good idea, and I worry about what effect that will have on people's sleep. So the message is that blue light isn't bad. It's just the timing of blue light that we want to be cautious about.