Sleep is one of those things that we really take for granted. If you were to ask anyone about the health implications of sleep, undoubtedly they would respond with “Why, yes, of course, sleep is important to health!” And yet, as a nation, we are sleep deprived to a massive degree.
The nature of sleep itself and why we do it is poorly understood, but we do know some basics. For starters…
LACK OF SLEEP MAKES YOU SICK
Sleep deprivation has been linked to a number of chronic diseases, including most of the Big Nasties that kill or cripple so much of our population- heart disease, stroke, and diabetes. How could lack of sleep be responsible for all of those?
Studies show that the harmful effects of sleep deprivation include physiological signs associated with increased stress, like an increase in blood pressure, an impaired control of blood glucose levels, and an increase in systemic (whole-body) inflammation. That last one- systemic inflammation– has been linked over and over again to pretty much every chronic disease process that plagues us as a nation. In fact, markers of inflammation are starting to be thought of as better markers for heart disease than the old standby of cholesterol testing.
How does that happen? Poor sleep leads to an increase in a hormone called “cortisol”, which is responsible for a lot of those inflammatory effects. But it’s not the only hormone affected by lack of sleep.
LACK OF SLEEP MAKES YOU FAT
It seems counter-intuitive, but too little sleep can lead to weight gain. Most people think that those lazy bums sleeping a full eight hours are going to be the ones expanding around the midsection, but the opposite is actually the case.
During sleep, our bodies secrete hormones that help control our appetite, regulate our energy metabolism, and process glucose properly. Poor sleep is associated with increases in the secretion of insulin following a meal. Insulin is a hormone that regulates glucose processing and promotes fat storage; higher levels of insulin are associated with weight gain and pose a risk factor for developing diabetes.
Insufficient sleep is also associated with lower levels of leptin, which is the hormone that tells the brain that it has had enough food already and needs to knock it off, as well as higher levels of ghrelin, a hormone that stimulates appetite. So, as you might imagine, poor sleep can result in our wanting to keep stuffing our faces even after we have eaten a reasonable amount of food. It also makes us more likely to binge on the sweet stuff that satisfies the craving for a quick energy boost.
Plus, not getting enough sleep may leave us too tired to get up off of our butts and go exercise, or at least make us tired enough that we don’t do as intense of a workout as we normally would. Fewer calories burned leads to… you guessed it… more weight gain.
LACK OF SLEEP MAKES YOU DUMB
A lot of us assume that the brain is switched “off” while we sleep. Nothing could be further from the truth. In fact, some researchers believe the brain is more active while we’re asleep than when we’re awake.
What’s going on in there while our eyes are shut? One of the many functions of sleep appears to be the processing of memories, including learning. Our brain integrates and refines our memories and makes sense of them in ways we can’t while we’re still awake.
Studies show that learning is absolutely dependent on sleep. Not just beforehand; a proper night’s sleep after learning is the magic window of opportunity to really allow your brain to lock in all of the benefits of practicing some skill during the day. After that first night, the opportunity is lost.
LACK OF SLEEP MAKES YOU DEAD
Poor sleep habits are associated with lower life expectancy. Data from three large cross-sectional epidemiological studies reveal that sleeping five hours or less per night increased mortality risk from all causes by roughly 15 percent. Simply put, people who get enough sleep live longer than people who don’t.
Part of that is because sleep-deprived people are more likely to screw up and hurt themselves. A study of sleep-deprived medical residents found that after a 24-hour shift, they had an almost three times greater chance of being in a car crash. That doesn’t even touch industrial accidents or other pitfalls that a sleep-deprived person may fall prey to.
There’s more to it than that. You may recall our discussion of Growth Hormone in our talk on exercise, and its importance in maintaining youth for as long as possible. Well, Growth Hormone doesn’t stay at a consistent level in the body throughout the day. On the contrary; Growth Hormone comes in surges at various points throughout the day, and the biggest one occurs while you’re sleeping.
People vary in how much sleep they need, but the old standby of eight hours is a good guide. You definitely don’t want to get less than seven hours a night.
And the quality of sleep matters, as well. Avoid caffeine at night, and alcohol as well. Oh, you might think that because alcohol is a depressant, it will help you get to sleep, but the truth is, after a few hours, alcohol metabolism kick-starts certain arousal mechanisms that mess up the quality of your sleep. So it might help you fall asleep, but the quality of sleep is poor.