How Exercise Enables Sleep

As Americans, our minds have long been fatigued and our bodies far from movement.
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Americans are sleepless, and are worse for it. The current economy is driving a rising prevalence of sleep complaints, particularly insomnia, at a time when few Americans cannot afford to either lose sleep or absorb new costs in investigating and treating it. Much of the treatment of sleep disorders involves detailed, labor-intensive investigations, medications and time-consuming behavioral therapy. When combined with dedicated patient education by board certified experts, these efforts can be highly effective. Sadly, many patients receive only a hastily scribbled pharmaco-therapeutic treatment in isolation, which is devoid of the educational and behavioral interventions they need. This sets them on a course for treatment failure.

Even today, 30 years after California's Stanford University began advocating the practice of medicine focused on sleep, few patients understand there is a field specifically dedicated to the study of sleep. When it comes to treatment of sleep disorders, even fewer understand they can engage in behaviors which can help them manage their own sleep. Few people realize the role that exercise can play in facilitating healthy sleep. When, after all, was the last time you were "prescribed" exercise at the doctor's office?

I recently wrote of the impact of my first few classes at SoulCycle in these columns, struck by the power and simplicity of the concept. Central to the theme of SoulCycle is a collaborative approach: instructors work hard to combine the principles of aerobic exercise to muscle exhaustion, recovery to pull back from lactic acidosis, and endurance building. They are evidently very skilled in how they plan monstrously efficient exercise routines, which leave one sweltering and panting -- within minutes, every fiber of one's being is at work. One can burn up to 600 calories or more an hour, equivalent to crosscountry skiing or vigorous horseback riding. But at SoulCycle, instructors also add a fascinating element of engaging the brain and the mind, which is a brilliantly sophisticated tool at pushing ourselves further. As one instructor put it, "Your mind is already tired, but your body is not. You can change it!" Their motivational techniques and guided imagery takes movement, and, in my opinion, turns it into medicine.

As Americans, our minds have long been fatigued and our bodies far from movement. We don't believe we can change how we live and certainly not how we sleep. Sleep needs vary between individuals but can range from 5.5 hours for the rare and very envied short sleeper, to as much as 10.5 hrs for the long sleeper. Most Americans however, never get to discover how much sleep they need, constantly forced to operate on severely sleep-deprived schedules. When we do sleep, our sleep is compressed and fraught. Unable to unwind, Americans find themselves pressured and alerted just when they need to relax and drift off.

Instead, as a nation we resort to behaviors which are ultimately sleep thieves: television, eBay, Facebook, even Farmville (yes its true, take it from my patients). As a result, instead of the customary five or so sleep cycles -- the oscillations between non-dream and dream sleep which occur every 60-90 minutes -- many Americans experience far fewer. Early risers have often abandoned bed long before the longest and most intense dream sleep period which unfolds in the early hours of the morning.

Dream sleep is believed to be associated with CNS development, memory formation and in fact dream sleep deprivation is also associated with heightened pain insensitivity. Yes, those very early starts may not be quite so good for you as you think. And, if we are burning the midnight oil, working long days and still insisting on catching up with late night television, our sleep in such a curtailed time period may not consist of much else except non-dream sleep because the cumulative effect of lack of sleep will lead to a preference of non dream "sleep debt" to be paid of first. We become, therefore, not only chronically sleep deprived, but also chronically sleep deprived.

So how do Americans treat their own sleep complaints?

Well, the most common substance Americans resort to for help sleeping is alcohol. Depending on which sources you read, six to 13 percent. of Americans self-medicate their sleep with alcohol. In a group of Americans experiencing chronic insomnia (symptoms persisting more than four weeks) that percentage rises to 35. The group which most commonly self medicates with alcohol for sleep disorders: the over-75-year-old "insomniac" woman where over 75 percent self medicate with alcohol.

Why is this the case? Well, of all the individuals experiencing sleep disorders, fewer than six percent will ever seek out a physician specifically to address the issues pertaining to their sleep. The other 94 percent will never bring the issue to attention, and, as physicians, we are notoriously poor at broaching the subject ourselves. So, most experiencing insomnia go unnoticed, and untreated by my fellow physicians.

In contrast, these same tired and sleepless Americans are very much noticed by a brisk and aggressive over-the-counter industry developing "sleep aids" in the form of "PM" formulations which do little other than attempt to smother symptoms with crude sedatives. In the exhausting daytime which follows such poor sleep, patients seek out RedBull, Monster Bean, Volt and other increasingly popular energy drinks which fuel our sleep-deprived, gaming adolescents, our fellow shift working bread-winning adults, or our harried, single parents. Recently, one of my patients disclosed he was "reliant" on a five shot espresso drink from Starbucks every morning! Only after meeting him did I start asking my patients what exactly patients are buying at America's hippest cafe counter.

"You ask for five shots in your espresso and they sell it to you?" I asked, incredulously, as if a barista would try and deter such extreme consumption.

"Oh Doctor, they sell a four shot espresso version, I just ask for 'an extra shot to go'" I guess I need to look at the Starbucks menu more closely.

In our exercise-obsessed nation -- either obsessed with doing too much exercise or with our guilt about doing none at all -- the role of exercise in promoting sleep has been entirely absent.

Exercise has a number of interesting impacts on sleep. Of course, being neurotically overscheduled, Americans don't always get a chance to exercise at the best time possible to help sleep, but beginning a conversation about this is always a good place to start.

Exercise promotes slow-wave sleep, also called Stage 3 sleep or delta sleep. Everyone can relate to slow-wave sleep when you imagine a five-year-old who has fallen asleep even though the house is literally rocking with a Super Bowl party. It's a deep, intense sleep from which is hard to rouse an individual. We call it "slow-wave sleep" because when we measure the brainwaves, (the EEG), the frequency of the waves is very slow, and the waves are very tall and deep. While we don't always know why, slow wave sleep is the special component of sleep which makes us feel refreshed and rejuvenated in the morning. It is what gives us a sense of feeling restored in the morning.

Slow-wave sleep also has other functions too. It is closely coupled with the release of growth hormone. Children with conditions that interrupt or truncate slow-wave sleep, like chronic, untreated or sub-optimally treated asthma can frequently experience the deleterious impacts of growth hormone deficiency. Yes, our mothers were right. If we don't go to sleep, on time we may not grow to be as tall and strong as we would otherwise.

Intriguing studies have examined the properties of slow-wave sleep in serious athletes. Investigators studied the sleep of athletes who routinely run 10,000 meters daily and compared it to the sleep of people like the rest of us -- those who do not!

They subjected the sleeping athletes to a noise stimulus, not loud enough to wake the subject but enough to produce a flicker in their sleep architecture, a so-called arousal. We measure arousals as elevated frequencies which accelerate above background sleep brain waves. The accelerations must last for at least three seconds as we define arousals in a sleep study. Anything can cause these events, from snoring, to a baby crying, pain, the sound of a pager, even heartburn.

In their experiment, researchers used a defined noise stimulant, again loud enough only to cause a flickering acceleration of the arousal above background EEG (brain waves) but not enough to wake the athlete. They repeated this noise insult on the non-athlete 'controls' in the study -- people who were identical in every way -- age, sex, lack of medical diagnoses and so forth, except for the fact they were not intense, habitual runners.

The researchers found that the athletes -- even though they had been subjected to stimuli which clearly disrupted sleep architecture -- woke in the morning feeling refreshed. On the other hand, the controls, the average person who did not exercise vigorously felt terrible, as if they hadn't had enough sleep! Their slow-wave sleep was not refreshing. The slow-wave sleep in the regular exercisers was somehow protective, unperturbed and intact in the face of stimuli and still conferred a feeling of restoration in the morning.

We know now from further studies that this kind of intact sleep is also hugely protective against pain, including chronic pain. Intact sleep, sleep integrity so to speak, is an effective analgesic. Those with fragmented, disordered sleep, experience a heightened response to painful stimuli. There is something very protective about intact sleep and a defense against pain.

The other beneficial quality about timed exercise concerns its ability to elevate core body temperature. We burn a lot of energy while engaged in exercise, and that energy generates heat. It takes the body hours to cool down by tiny degrees in order to return to baseline. Yet it is a falling curve of cooling body temperature that so invites sleep onset. Our body temperature is, like many rhythms, closely aligned around the 24-hour clock to fluctuate in set patterns -- we call these patterns circadian rhythms, from the Latin, circa, meaning around and diem, meaning day.

These patterns are close to a day in cycle, give or take 20 minutes. This is why, when you have worked all night overtime on a shift which you don't normally do, even though you are bone tired from a hard day's night and you crash into bed, by 11 am you are buzzing awake and very angry at not being able to sleep longer. That's because, being used to working in the daytime, the body temperature is busy cresting to a peak at 11 a.m., which is alerting and not conducive to sleep. Exercise can shift that curve and change the gradient of the slope. Engaging in vigorous exercise which ends five hours before desired sleep time, will certainly shorten the time taken to fall asleep. It will also increase percentages of slow-wave sleep, or deep sleep and help us feel more rested.

All my patients learn about this strategy. We examine whether they are engaging in the dubious bargain of trading sleep for late night TV. I remind them to use their DVRs if they can, and we talk about using some of their early evening or late afternoon time to engage in exercise as a way to change their relationship to sleep. Once patients understand it, they are almost excited to start experiencing the effects. Many of them choose to use a National Sleep Foundation log to monitor their progress and come back and report to me in a month's time. Some of my patients are self-monitoring, using the attractive and imaginative ZEO device -- I am actually having fun with that myself this week.

Just for fun, I decided to measure my sleep patterns using a consumer sleep monitoring device on Sunday night after I had exercised in my spinning class. I was pleased to see that the night after I had been spinning, I logged 54 minutes of slow-wave sleep according to my sleep monitor. As I looked at the reading in the morning and studied the digital hypnogram (literally a landscape of my night's sleep) I thought to myself, "hmm, I really can spin myself to sleep, all the way to deep sleep in fact.

Talk about movement as medicine: SoulCycle is movement as medicine, and movement as sleep medicine. SoulCycles really do make SleepCycles. The science is there to support it.

Do what I do. Put yourself at the wheel of your own sleep. Start your ride to refreshment and rejuvenation. Join the SelfCare Sleep Movement and start by spinning yourself to sound, sound sleep.