By Dr. Mercola
If you're sleep deprived for a night or two (or more), you expect to feel groggy and irritable.
But losing sleep impacts your body on a far deeper level, too, increasing your risk of obesity and chronic diseases like diabetes.
New research has shed some light onto why sleep deprivation may be so damaging to your health, as it linked lack of sleep to serious impairments in the way your body responds to the hormone insulin.
Lack of Sleep Impairs Your Body's Insulin Sensitivity
Impaired insulin sensitivity, also known as insulin resistance, occurs when your body cannot use insulin properly, allowing your blood sugar levels to get too high. Insulin resistance is a precursor to type 2 diabetes as well as a risk factor in many other chronic diseases.
In fact, controlling insulin levels is one of the most powerful ways to reduce your risk of chronic diseases, including high blood pressure, heart disease, and cancer. The increase in insulin-related diseases we're now seeing is largely due to lack of exercise combined with the excessive consumption of fructose and carbohydrate consumption in the average American diet … but it also appears that lack of sleep is likely playing a part in the equation too.
According to research published in the Annals of Internal Medicine,1 after four nights of sleep deprivation (sleep time was only 4.5 hours per night), study participants' insulin sensitivity was 16 percent lower, while their fat cells' insulin sensitivity was 30 percent lower, and rivaled levels seen in those with diabetes or obesity. The study's senior author, Matthew Brady, an associate professor of medicine at the University of Chicago, told CNN:2
"This is the equivalent of metabolically aging someone 10 to 20 years just from four nights of partial sleep restriction. Fat cells need sleep, and when they don't get enough sleep, they become metabolically groggy."
Not Enough Sleep Has Serious Consequences To Your Metabolism
When you're sleep deprived, leptin (the hormone that signals satiety) falls, while ghrelin (which signals hunger) rises. In one 2010 study,3 researchers found that people who slept only four hours for two consecutive nights experienced:
- 18 percent reduction in leptin
- 28 percent increase in ghrelin
This combination leads to an increase in appetite. Additionally, sleep deprivation tends to lead to food cravings, particularly for sweet and starchy foods. Researchers have suggested that these sugar cravings stem from the fact that your brain is fueled by glucose (blood sugar); therefore, when lack of sleep occurs, and your brain is unable to properly respond to insulin (which drives glucose into brain cells) your brain becomes desperate for carbohydrates to keep going. If you're chronically sleep deprived, consistently giving in to these sugar cravings will virtually guarantee that you'll gain weight.
As mentioned, getting too little sleep also dramatically decreases the sensitivity of your insulin receptors, which will raise your insulin levels. This too is a surefire way to gain weight, as the insulin will seriously impair your body's ability to burn and digest fat. It also increases your risk of diabetes. In short, sleep deprivation puts your body in a pre-diabetic state, which can lead to increased weight and decreased health.
Can't Sleep? Here are 10 Reasons Why…
If you're staying up late to watch your favorite TV program or intentionally pulling an all-nighter to cram for a test, you know why your sleep is lacking. But far more often, Americans have trouble sleeping and they don't know why. According to the National Sleep Foundation, few Americans get sufficient amounts of sleep. Only four in 10 respondents said they got a good night's sleep every night, or almost every night, of the week,4 and a separate poll found 43 percent of Americans reported "rarely or never" getting a good night's sleep on weekdays.5
There are many factors that can influence your sleep. For my complete recommendations and guidelines that can help you improve your sleep, please see my article 33 Secrets to a Good Night's Sleep. Following are 10 often-overlooked factors that might be interfering with your sleep:
- Too Much Light in Your Room
Even the tiniest bit of light in the room, including those emitted by electronic devices, can disrupt your pineal gland's production of melatonin and serotonin, thereby disrupting your sleep cycle.
So close your bedroom door, install black-out drapes, use a sleep mask, get rid of night-lights, and refrain from turning on any light during the night, even when getting up to go to the bathroom. If you have to use a light you can use a red flashlight, as that wavelength of light has a minimal impact on melatonin production..
- Exercising Too Close to Bedtime
Exercising for at least 30 minutes per day can improve your sleep. However, don't exercise too close to bedtime (generally not within the three hours before) or it may keep you awake.
- Drinking Alcohol Before Bed
Although alcohol will make you drowsy, the effect is short lived and you will often wake up several hours later, unable to fall back asleep. Alcohol will also keep you from entering the deeper stages of sleep, where your body does most of its healing.
- Your Bedroom is Too Warm
Many people keep their homes and particularly their upstairs bedrooms too warm. Studies show that the optimal room temperature for sleep is quite cool, between 60 to 68 degrees F. Keeping your room cooler or hotter can lead to restless sleep. When you sleep, your body's internal temperature drops to its lowest level, generally about four hours after you fall asleep.
Scientists believe a cooler bedroom may therefore be most conducive to sleep, since it mimics your body's natural temperature drop.
- Caffeine is Keeping You Awake
Caffeine has a half-life of five hours, which means some will still be in your system even 10 hours later, and 12.5% 20 hours later (see the problem?). Plus, in some people caffeine is not metabolized efficiently, leaving you feeling its effects even longer after consumption. So, an afternoon cup of coffee or tea will keep some people from falling asleep at night. Be aware that some medications contain caffeine as well (for example, diet pills).
- You're Watching the Clock
The more you watch the clock when you wake up in the middle of the night, the more stressed and anxious you will become, and the more you may actually "train" yourself to start awakening at the same time each night. The solution is simple: Remove the clock from your view so you actually have to sit up or change positions to see the clock.
- Watching TV to Help You Fall Asleep
The artificial glow from your TV can serve as a stimulus for keeping you awake and, possibly, eating, when you should really be asleep. Further, computer and TV screens (and most light bulbs) emit blue light, to which your eyes are particularly sensitive simply because it's the type of light most common outdoors during daytime hours. As a result, it can disrupt your melatonin production and further interfere with your sleep.
- Worrying in the Middle of the Night
If stress keeps you up at night, try keeping a "worry journal" next to your bedside so you can jot down your thoughts there and clear them from your head. The Emotional Freedom Technique (EFT) can also help balance your body's bioenergy system and resolve some of the emotional stresses that are contributing to your insomnia at a very deep level. The results are typically long lasting and improvement is remarkably rapid.
- Do Not Eat Three Hours Before Bed
Although you might struggle with this initially, it is ideal to avoid eating any foods three hours before bed, as this will optimize your blood sugar, insulin and leptin levels and contribute to overall good health.
The nicotine in cigarettes is a stimulant, which can keep you awake much as though you just drank a cup of coffee.
How Much Sleep is "Enough"?
Download Interview Transcript
There is no perfect answer to this question because the answer depends on a large number of highly individual factors. The general consensus seems to be that most people need somewhere between six and eight hours of sleep each night. You are seriously fooling yourself if you are sleeping less than six hours a night and saying you don't need much sleep to be healthy.
There's compelling research indicating that sleeping less than six hours may increase your insulin resistance and risk of diabetes. And less than five hours of sleep at night may double your risk of being diagnosed with angina, coronary heart disease, heart attack or stroke. Interestingly enough, the same appears to be true when you sleep more than nine hours per night.
The question of the ideal amount of sleep is a topic Dr. Rubin Naiman -- a clinical psychologist, author, teacher, and the leader in integrative medicine approaches to sleep and dreams -- has addressed on numerous occasions throughout his career as a sleep expert (as well as in the video above), and he agrees: people want a number, but this 'number' must be as individual as the person asking for it.
"I think asking 'how many of hours of sleep should I get?' is like asking, 'Doctor, how many calories should I eat?'" he says. "Of course the answer to that depends on who that person is. It's so individual. It also depends on the quality of those calories. Again, a lot of people are knocking themselves out night after night after night with sleeping pills. They may be getting seven to eight hours, but is it sleep? It looks like sleep. It might feel like sleep, but you know what, it's not really sleep. That's part of the question too—the quality of it."
Again, for a comprehensive sleep guide for quality sleep, please see my article 33 Secret's to a Good Night's Sleep.