Sleep serves so many functions that are important for health, some of which are still being discovered. For example, recent research shows that sleep helps your brain “detoxify,” remove toxic metabolic by-products that build up along with damaged or misfolded proteins. How does it do this? Inside your brain is a special lymphatic system called the g-lymphatics. As you sleep, these channels open up and drain toxins from your brain. Pretty amazing, huh?
Along with its role in detoxifying, sleep plays a number of vital roles – it helps consolidate memories and bolster immune function. We also know that sleep plays a key role in weight control. If you’re trying to lose weight and shortchanging yourself on sleep, you may have a harder time reaching your ideal body weight. In one study, dieters that reduced the number of hours they slept over a 2-week period, the amount of body fat they lost dropped by 55%, even when they ate the same diet.
One way curtailing sleep works against weight loss is by boosting appetite. Studies show that sleeping too little markedly impacts the activity of two major appetite hormones, leptin and ghrelin. Leptin is a hormone that signals your brain that you have sufficient fat stores and don’t need to eat more. Ghrelin has the opposite effect – it boosts appetite, particularly for foods high in carbs or fat. What’s more, when you’re sleep-deprived, your ability to resist sugary temptations is compromised and you find yourself reaching for whatever is available. More often than not, it’s something that wouldn’t make the list of healthiest foods. When you’re tired, how motivated are you to seek out or cook a healthy meal? So, those good intentions to eat healthy fall by the wayside.
Lack of Sleep Can Alter Your Metabolic Rate as Well
As if making you hungrier isn’t enough, sleep deprivation makes it easier to pack on the pounds in another way – by slowing your metabolic rate. Your basal metabolic rate is regulated by your thyroid. Your thyroid produces hormones, T3 and T4, under the influence of TSH produced by the pituitary gland in your brain. TSH stimulates the production of thyroid hormones and these hormones, in turn, boost metabolic rate. One study showed that after 6 days of sleeping 4 hours nightly, the nightly rise in TSH fell by 30%. Fortunately, this drop is reversible. Once the subjects resumed their normal sleeping patterns, their TSH returned to normal. Other studies show that lack of sleep raises TSH. Regardless, lack of sleep seems to disrupt regulation of thyroid activity.
Lack of sleep negatively impacts metabolic function in another way – by altering the way your body processes glucose. In one study, subjects who slept 4 hours night for 6 nights showed significant reductions in the ability to clear glucose from their bloodstream. In response to being sleep deprived, insulin sensitivity dropped significantly.
Studies show it can take up to 40% longer to properly regulate blood sugar after eating a meal high in carbs when you’re sleep deprived. Over time, this places added stress on your pancreas and can lead to type 2 diabetes. A meta-analysis of 11 studies found that the risk of type 2 diabetes went up as sleep duration shortened, although the response was U-shaped. In the study, both short and long sleep durations were associated with a higher risk of type 2 diabetes.
Sleep Architecture is Disrupted Too
The optimal amount of sleep? Based on this analysis and other sources as well, 7 to 8 hours nightly. So, not sleeping enough can contribute to weight gain and also adversely impact your metabolic health. When you cut your sleep time back to below six hours, you experience less slow-wave sleep. Slow-wave sleep is the most restorative to your body and interruptions in slow-wave sleep are the most detrimental to your metabolic health.
Lack of sleep also places stress on your body. In response, you get the release of stress hormones, including cortisol. Not only is cortisol bad for your waistline – it leads to fat storage around the tummy, it also worsens insulin sensitivity and blood glucose and depresses immune function. That’s one reason you’re more susceptible to catching a cold when you don’t sleep enough. A number of studies link sleeping less than 7 hours a night with a higher risk of mortality from heart disease. At the same time, sleeping longer than 9 hours a night is also associated with higher mortality.
How might sleeping too little affect your risk of death? One theory is that short sleep durations increase the odds of other health problems, including obesity and type 2 diabetes, that shorten lifespan. Lack of sleep can also trigger low-grade inflammation, a contributing factor to a number of health problems. But what about sleeping too much? Why is that a risk? Researchers have no real explanation for this but think there may be confounding factors, like depression or underlying health problems, that explain why sleeping longer is linked with higher mortality.
What if You Can’t Sleep?
Now that you know that lack of sleep can affect your metabolism AND your metabolic health, you’re probably eager to get your ZZZs – but what if you can’t sleep? First, check with your doctor. Undiagnosed health problems, particularly sleep apnea, and some medications can interfere with sleep. If you’re all clear from a health standpoint, try these tips:
· Darken your bedroom so that you’re sleeping in total darkness
· Have a regular sleep schedule, even on weekends. Stick to it.
· Lower the temperature of your bedroom to 65 degrees. Cooler temperatures are more favorable for sleep.
· Remove all electronics from your bedroom & avoid blue light from devices within 2 hours of bedtime.
· Have a relaxing bedtime ritual – warm bath, cup of herbal tea, stretching, meditation.
· Add a white noise device to your bedroom to help you relax.
The Bottom Line
Sleep really IS important – and lack of it can negatively impact your metabolic health. Make sure you’re getting enough.
WebMD. “Sleep More, Weigh Less”
Medscape.com. “The Impact of Sleep Deprivation on Hormones and Metabolism”
Diabetes Care. 2015 Mar;38(3):529-37. doi: 10.2337/dc14-2073.
Sleep. 2010 May 1; 33(5): 585–592.
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