What is the magic sleep number?

Bill Clinton (ex-President). Tracy Morgan (comedian). Cindy Lynn Baldwin (motor vehicle driver). What do these seemingly unrelated individuals have in common? The answer is that each either suffered from sleep deprivation or was victimized by someone who was sleep-deprived.

There is no doubt that all of us have gotten too little sleep at some point in our lives. For some of us, it is an isolated occurrence precipitated by a specific event, such as a death in the family or an upcoming stressful meeting. However, there is increasing evidence that America is becoming a country of chronically sleep-deficient citizens.

According to a recent report from the Centers for Disease Control and Prevention, the percentage of adults sleeping fewer than 6 hours per night has increased by 31% since 1985. There are likely a number of explanations for this. They include the increasing demands of a 24-hour society, the increased use of artificial lighting, changing lifestyles that encourage late-night activities, and the widespread use of electronic devices such as tablets, laptop computers, and smartphones. The latter are particularly bad for sleep health because they emit blue wavelength light, which negatively impacts your body’s natural sleep-wake cycle and interferes with the onset of sleep.

Negative Health Effects of Sleep Deficiency

There are important consequences of insufficient sleep. On an individual level, sleep deficiency makes one more irritable and depressed, slows reaction times, and negatively affects mental and physical performance. In fact, 18 hours of continuous wakefulness has the same adverse effect on reaction time as being legally drunk! (The driver of the truck that hit Tracy Morgan’s vehicle had been awake for 28 hours straight.)

In addition, adequate sleep is necessary for optimal learning and memory. Experiments have shown that staying awake all night impairs the learning of new information. Therefore, the proverbial “all-nighter” that some of us practiced when we were in school probably worsened our test performance rather than helped it.

Chronic sleep deprivation exacts a toll as well. One and a half weeks of 6 hours’ sleep per night can have the same impact as staying awake for 24 hours straight. And just as important as the behavioral consequences of inadequate sleep are its negative effects on health. It is now becoming increasingly evident that sleep deficiency is a risk factor for hypertension, heart disease, diabetes, and — not surprisingly — earlier death. In addition, inadequate sleep changes the levels of the hormones that control appetite, and this leads to increased hunger and a greater tendency for weight gain. Thus, sleep deficiency is a risk factor for obesity!

At Least 7 Hours of ZZZs Nightly

Because both acute and chronic insufficient sleep are bad for health, the CDC’s Healthy People 2020 campaign includes a goal to reduce sleep deficiency. However, the goal doesn’t specify exactly how much sleep is needed. To remedy this omission, the American Academy of Sleep Medicine and the Sleep Research Society, the two leading professional organizations in the fields of sleep medicine and research, released a joint consensus statement.

Based on current evidence, adults should aim for at least 7 hours of sleep a night for optimal health, and that getting fewer than 6 hours of sleep is associated with worse health outcomes. At the same time, there is insufficient evidence to determine whether getting between 6 and 7 hours of sleep a night is bad for health. A similar document from the National Sleep Foundation largely came to the same conclusions.

So, is 7 hours the magic sleep number? Perhaps. Future research may lead to some refinements, but for now, it should be the goal.

Can you make up for being short of sleep for a few days? The answer is not straightforward.  Many individuals get inadequate sleep on workdays and then attempt to recover their lost sleep on weekends. In such cases, there is generally an improvement in mood, as well as mental and physical performance, after “recovery” sleep. However, being able to reverse the effects of inadequate sleep on physical health is less certain. Recent observations indicate that lack of sleep may cause persistent negative effects on heart rate and the secretion of various inflammatory molecules. These may be risk factors for heart disease.

The Remedy is Simple

What can be done about sleep deficiency? The solution is simple: Get more sleep. On a personal level, this means making better lifestyle choices — for example, choosing to go to bed earlier in the evening instead of staying up to watch late-night television. For institutions and employers, this means creating a work environment that values the beneficial results of having employees who are not sleep-deprived: namely, fewer employee sick days, better productivity, and less use of health insurance benefits.

Although the prescription for more sleep appears to be inexpensive with no costly medications required, the personal and logistical hurdles can be formidable. Nevertheless, a target of at least 7 hours of sleep per night can be achieved. If sufficient numbers of individuals, businesses, and institutions make sleep a priority with status equal to good nutrition and fitness, then our society will be healthier and more productive — goals we all value.

The post What is the magic sleep number? appeared first on Harvard Health Blog.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s