Get 7 to 9 hours of sleep and reap the benefits


You have probably noticed on the streets or in the grocery store: Americans are a great deal heavier than they were two or three decades ago. And statistics confirm it: nearly 70 percent of American adults are now classified as either overweight or obese; and the rate of obesity among children has tripled since 1980.

Many possible factors have been proposed, including sugar-sweetened beverages, lack of exercise, and super-sized fast food portions. All have legitimate claims. Two other factors–sleep and psychosocial stress--are not mentioned as frequently although they too apparently play a prominent role.

On a personal level, you are probably aware of the subtle connections between sleep, stress and obesity. You have been under pressure to complete a difficult project. To meet your deadlines, you have been cutting back on your sleep, and that, in itself, is creating additional stress. 

As your energy level ebbs, you find yourself drinking more coffee and that is making you jittery. Your exercise routine has been ditched, and yon don’t have time to prepare or even sit down for a proper meal. All too often you reach for ready-to-eat comfort a bag of chips or a candy bar from the vending machine. You are eating these snacks knowing full well the effect they will have on your weight and waist line, but that only increases the stress. It’s a vicious circle, and there is more than anecdotal evidence to support it.

Cortisol and Stress

Stress leads to increased release of cortisol, which, in turn, inhibits the fat-burning gene in the liver. The result is weight gain, particularly abdominal or visceral fat. A 2011 meta-analysis [J. Wardle, et al, Obesity, 2011;19:771-778] confirmed the positive correlation between stress and weight gain.

In most persons, cortisol is at its highest level in the morning, as we adjust to getting started on the day’s activities. The cortisol level then tapers off throughout the day until it reaches its lowest level just before bedtime. Chronic 
Stress at bedtime is bound to interfere with sleep, and insomnia itself tends to raise the cortisol level even more throughout the day. 

Americans Sleep Less

Even without stress, many individuals today choose to sleep less. And the trend is in the direction of less sleep.

In 1960, large surveys found a median sleep duration of 8.0 to 8.9 hours. By 2000, sleep duration had fallen to 6.9 to 7.0 hours; and today, it’s believed, many Americans get by on only 5 to 6 hours a night.

Some epidemiological studies have found that individuals getting less than six hours sleep a night are about 50 percent more likely than others to be overweight or obese. But sleep quality, as well as duration, is important. 

Appetite Control Diminishes with Less Sleep

In addition to the effect of stress hormones, sleep loss also affects hormones that control appetite. And recent studies have found that sleep loss results in an increase in appetite that exceeds the extra calories demanded by wakefulness.

Two hormones that have been found important in regulating appetite are leptin and ghrelin. Leptin, released by fat cells, sends a satiated signal to the brain, suppressing appetite. On the other hand, ghrelin, a peptide secreted by the stomach, stimulates appetite.

Sleep Loss = Tired + Hungry

Sleep loss clearly makes you feel not only tired but excessively hungry. You are as tired as if you had run a marathon, but your metabolism is slowed because of lack of sleep.

Yet another factor is sleep timing or what some have called social jet lag. When you cross several time zones during travel or when you do shift work, your body’s circadian rhythms are thrown out of whack.

Most of us have a comfortable internal rhythm: we are either early birds or night owls, but our work and social schedules do not always match that internal rhythm. Those of us who hate to hear that alarm at 7 a.m. every week day compensate by sleeping in on weekends.

So if you’re constantly concerned about your inability to control your weight, don’t lose sleep worrying about it. Instead, focus on re-adjusting your schedule and your priorities so that you are sure to get seven to nine hours of sleep a night.

Adding an extra hour of sleep each night isn’t going to make you instantly slimmer. But if you’ve been in serious sleep debt–and many Americans are–you will eventually start feeling the difference in terms of stress, body mass, health and overall well being.

Aurelian Bidulescu, et al, “Interaction of sleep quality and psychosocial stress on obesity in African Americans: the Cardiovascular Health Epidemiology Study (CHES),” BMC Public Health, 2010;10:581.
Denise Mann, “Will better sleep help you avoid extra pounds?” WebMD Feature, reviewed by Hansa D. Bhargava, M.D., April 30, 2013.
National Sleep Foundation, “Obesity and sleep.”
Rebecca Nugent, Ph.D., et al, “Modeling the relation between obesity and sleep parameters in children referred for dietary weight reduction intervention,” Southern Medical Journal, 2014;107(8):473-480.
Byron J. Richards, “Lack of sleep, stress, adrenals, and obesity,” New and Views, September 25, 2008.
Femke Rutters, Ph.D., M.Sc., “Stress, sleep and social jetlag: the obesity epidemic’s psychosocial side,” Medscape, October 19, 2015.
Sarah E. Tom, Ph.D., MPH, and Abbey B. Berenson, M.D., Ph.D., “Associations between poor sleep quality and psychosocial stress with obesity in reproductive-age women of lower socioeconomic status, Women’s Health Issues, September/October, 2013.
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Alexandros N. Vgontzas, M.D., et al, “Obesity and self-report short sleep duration: a marker of sleep complaints and chronic psychosocial stress,” Sleep Medicine Clinics, March, 2009.

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