For many hundreds of years we have known the functions of three of the 4 basic drives in life-to eat, to drink, and to reproduce. But for fourth main biological drive—to sleep—has eluded science for years. Scientists asking “why we sleep” may have been asking the wrong question. All animals sleep and sleep persists with the evolutionary process. In the last 20 years, more researchers are asking what happens in our brains and in our bodies while we sleep. We spend one-third of our life sleeping! What happens during that time
Until recently, I considered sleep as a “pillar” of health along with diet and exercise. After doing a deeper dive into the research, I have come to appreciate that sleep is the foundation of good health. The physical and mental impairments of one bad night’s sleep are much greater than those caused by an equivalent absence of food or exercise.
Every major system, tissue and organ of the body suffers when you don’t get enough sleep. There are more than 20 large-scale studies that tracked millions of people over my years. All report the same thing--the shorter your sleep, the shorter your life
Sleep and Your Heart
One long term study of more than a half a million men and women of varied ages, races and ethnicities across 8 countries, showed that progressively shorter sleep was associated with a 45% increase risk of developing or dying from coronary artery disease within 7-25 years. The relationship between short sleep and heart failure remains strong even after controlling for other known cardiac risk factors, such as exercise, weight and smoking. Another study showed that adults 45 and older who sleep less than 6 hours at night are 200% more likely to have a heart attack or stroke during their lifetime that those sleeping 7-8 hours! Yet many of us choose to skip some sleep in order to “catch up” on work or prepare a craft project for our kids to work on the next day.
Lack of sleep keeps the sympathetic nervous system-the fight or flight or freeze-turned on. Over time, lack of sleep, removes the brake that prevents the heart from accelerating which in turn leads to increased blood pressure. At the same time, cortisol, one of the “stress” hormones is being constantly released which triggers the blood vessels to constrict or get smaller which increases the blood pressure, which increases your heart rate. And the cycle continues.
On top of that cycle, “growth” hormone-the great healer of the body- which normally surges at night, is shut off by sleep deprivation. Without the growth hormone, the lining of the blood vessels, the endothelium, is not able to repair and the arteries are more prone to atherosclerosis (hardening of the arteries). This hardening increases the risk of the arteries rupturing causing a stroke if it happens in the brain or a heart attack if it happens to one of the cardiac arteries.
Most people don’t worry about losing an hour of sleep. BUT think about this: In March, when most of us in the Northern Hemisphere, lose an hour of sleep due to the switch to daylight savings time, there is a spike in heart attacks the next day according to the researchers who tabulate hospital records. Similarly, in November when we “fall back” and gain that hour of sleep opportunity, the rate of heart attack plummets the next day. There is a similar relationship between traffic accidents, proving that the brain is just as sensitive as the heart to a very small disruption in sleep.
Sleep and Your Metabolism
Did you know that the less you sleep, the more you eat? And your body is not able to manages those calories effectively—especially the concentration of sugar in your blood. In short, sleeping less that 7-8 hours a night increases your probability of gaining weight, being overweight and significantly increases your risk of developing type 2 diabetes.
There are two hormones that control your appetite: leptin and ghrelin. Leptin signals the sense of feeling full so when your leptin levels are high, you don’t feel like eating. Ghrelin, does just the opposite. When its levels are high, we feel really hungry. When these hormones are not balanced it can trigger increased eating and we will gain weight. In several studies, healthy young adults were studied. In the first part of the study, they were allowed to sleep 8.5 hrs while being monitored. In the second part of the study, they were only allowed to sleep 4 to 5 hours. They received the same amount and type of food and the same amount of physical activity. When sleep was decreased to 4-5 hours, the participants felt “ravenous” the next day. When the circulating hormones of leptin and ghrelin were measured when sleep was cut short, there was decreased leptin and increased ghrelin. In other words, the participants lost their hunger control. In another study, participants were given more food when their sleep was cut short and they still felt hungry!! And in yet another study, when the sleep participants were allowed to eat a 2000 calorie lunch and then given access to a “snack food bar”, the participants who slept less ate at additional 330 “empty” calories compared to when they got plenty of sleep!!!
In similar studies where blood sugars were measured, when healthy people with no existing signs of diabetes or issues with blood sugar were limited to 4 hours of sleep per night for 6 nights, they were 40% less effective at absorbing glucose. When the blood results were shared with family doctors, the doctors immediately classified these people as pre-diabetic. That’s right. In 6 nights of less than optimal sleep, healthy folks were considered pre-diabetic!!
Sleep and Your Immune System
If you are like my, you may be wondering what are some of the best ways to boost your immune system these days. Studies show that people who don't get quality sleep or enough sleep are more likely to get sick after being exposed to a virus, such as a common cold virus. Lack of sleep can also affect how fast you recover if you do get sick.
During sleep, your immune system releases proteins called cytokines, some of which help promote sleep. Certain cytokines need to increase when you have an infection or inflammation, or when you're under stress. Sleep deprivation may decrease production of these protective cytokines. In addition, infection-fighting antibodies and cells are reduced during periods when you don't get enough sleep.
There are studies that show that people who get good sleep for a week prior to receiving a flu shot generate a more powerful immune response than those people who are sleep deprived when they receive the shot.
There is more research out supporting how lack of sleep is associated with a 40% increase in developing cancer. The reason is the natural killer cells of our body or cancer-fighting immune cells are reduced by as much as 70% in people who sleep 5 or less hours most nights of the week
For the last while whenever I have taken another course to learn more about how I can serve the women who come into see me and asked what I learned, I usually respond, “It goes back to the basics: you have to eat right, you have to move, you have to take care of your emotions and you have to get good sleep. It wasn’t until taking this deeper dive into the sleep research that I have come to understand how important sleep really is to our health. It is truly the foundation of health. Without good sleep, our bodies and are brain don’t work optimally.
Next week, I will talk to you about “sleep hygiene” or how to optimize yourself to get the sleep that you need to be and stay healthy.