You may do everything right or ALMOST do everything right – exercise most days of the week (strength and cardio training), eat a whole foods diet, and do yoga to relieve stress. Unfortunately, you’re still only getting 6 hours of sleep most nights. You might think that since you’re on track with everything else, you can let sleep slide. Not so! A number of studies show that adequate sleep is strongly linked with measures of health and even plays a part in weight control What you may not realize is lack of sleep also directly impacts the health of a vital organ, your heart.
Just One Night of Missed Sleep is Hard on Your Heart
Did you know that when you don’t sleep enough one night, it negatively impacts your heart the next day? In fact, a study carried out on healthy radiologists showed how quickly your heart suffers the effects of inadequate sleep. The participants were young and middle-aged men and women and their hearts were monitored before and after a 24-hour shift where they slept for only 3 hours. That’s pretty routine for some radiologist when they’re on call.
What they found was just one night of sleeping too little forced their hearts to work 10% harder the following day. In response to lack of sleep, blood pressure rose and the heart had to pump harder. Having to pump harder is beneficial when you’re exercising and delivering more oxygen to tissues but not so much when you’re sleep deprived.
Why does your heart have to work harder when you don’t sleep enough? Lack of sleep is a form of stress that changes the activity of your nervous system. Your sympathetic or “fight or flight” division of your nervous system takes over. This is the portion of your autonomic, or “automatic,” nervous system that turns on when you’re headed into battle or are preparing to fight a tiger. In response, your heart rate increases, your blood pressure rises, and your heart muscle pumps with more force.
Other studies show that even short-term sleep deprivation, a few nights of skimping on sleep, ignites a cascade of inflammatory changes that are harmful to your heart and blood vessels. Along with inflammation comes a decrease in insulin sensitivity. Such changes go along with insulin resistance, a syndrome that can lead to type 2 diabetes, yet it’s harmful in its own right. Insulin resistance is linked with heart disease, high blood pressure, obesity, and some forms of cancer.
When You Don’t Sleep Enough Longer Term
What if you burn the midnight oil more often or, even worse, every night? Chronic sleep deprivation is also bad for your heart. You see a drop in insulin sensitivity with short-term sleep deprivation but also when you don’t sleep enough long term. A number of studies show that adults who don’t sleep at least 5 hours nightly are at higher risk of developing type 2 diabetes – and if there’s one disease that’s likely to damage your heart, it’s diabetes. In fact, heart disease is the most common cause of death in people with this condition.
Another condition that places a burden on your heart is obesity. When you’re obese, your heart has to work harder and your risk of health problems, like diabetes, that damage to your heart and blood vessels goes up, including high blood pressure and metabolic syndrome.
How does chronic lack of sleep contribute to obesity? When you don’t sleep enough, you produce more of the stress hormone cortisol. Although cortisol has benefits when you’re in a stressful environment, persistent elevation of cortisol throws your immune system out of balance and can trigger blood-vessel damaging inflammation. Plus, cortisol also contributes to insulin resistance and obesity. When you don’t sleep long enough, it also throws your chief appetite hormones, leptin and ghrelin, out of balance. As a result, you start craving foods high in fat and sugar. In fact, research shows that people who regularly sleep less than 6 hours a night have a higher body mass index relative to those who slumber 7 or 8 hours on a regular basis.
Other Downsides of Lack of Sleep
If you strength train, you count on growth hormone, an anabolic hormone, to help you build strength and muscle size and your body secretes the most growth hormone during the deeper stages of sleep. In fact, according to a study in healthy men, when you’re deprived of sleep the nighttime release of growth hormone is greatly diminished. Plus, as mentioned, cortisol, a catabolic hormone, rises and this further interferes with gains in strength and muscle size. In addition, an elevated cortisol level, over time, can lead to muscle loss. The combination of muscle loss and a higher risk of obesity is a bad combination. Make sure you’re getting your sleep!
How Much Do You Need?
Studies show that between 7 to 8 hours per night is an optimal sleep schedule for most adults. Teens and children need more. Of course, sleep quality counts as well. These days, many of us spend time just before bedtime staring at a computer screen or iPhone. The blue light from these devices can interfere with sleep. If you’re having trouble falling or staying asleep, don’t use these devices within two hours of bedtime. If you must, adjust the setting for night mode where you’ll be exposed to less blue light. You can find instructions for doing this online. The reason blue light is detrimental to sleep is it interferes with the production of melatonin, a hormone produced by the pineal gland in your brain. Melatonin regulates your sleep-wake cycle and may also play a role in the regulation of body weight as well.
The Bottom Line
No doubt about it! Quality sleep is essential – not just for your heart but for your health as a whole. Make it a priority, not an afterthought. How much you sleep matters and the quality counts as well. Train yourself to turn out the lights at the same time each night, at a reasonable time. No burning the midnight oil. It’s bad for your health.
Telegraph Science. “Sleep deprivation puts strain on heart, scientists prove”
Prog Cardiovasc Dis. 2009 Jan-Feb; 51(4): 294–302. doi: 10.1016/j.pcad.2008.10.003.
Harvard Healthy Sleep. “Sleep and Disease Risk”
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