Editor’s note: This article is a reprint. It was originally published on August 17, 2017.
It is estimated that 73.6% of American adults over the age of 20 are overweight or obese. In children, 22.2% of those aged 12 to 19 are considered obese, 20.7% of those aged 6 to 11, and 12.7% of those aged 2 to 5.1 While exercise and especially diet certainly play a role in this epidemic, there is another often overlooked factor that can help people manage their weight with little effort. In fact, it doesn’t take anything other than getting more sleep.
Like overweight and obesity, insufficient sleep is a public health problem in the United States, and the two may be related. The Centers for Disease Control and Prevention (CDC) reports that 50 to 70 million adults have sleep or wake disorders, and more than 35 percent typically sleep less than seven hours per 24-hour period.2
Meanwhile, this lack of sleep has serious consequences: falling asleep unintentionally during the day (reported by 38% of survey respondents) and falling asleep while driving (reported by almost 5%). But it also leads to weight loss.
A slim waist and reduced weight can help you sleep better
Researchers in the UK looked at the link between sleep duration (sleep duration) and diet and metabolic health in more than 1,600 adults.3 Previous studies have linked sleep deprivation to an increased risk of metabolic diseases, including obesity, and this study found similar results. Sleep duration was negatively associated with body mass index (BMI) and waist circumference. In other words, the longer a person slept, the smaller their waist and the lower their BMI.
Specifically, people who slept an average of only six hours a night had waists that were more than an inch (3 cm) larger than those who slept nine hours a night.4 Shorter sleep durations have also been linked to lower levels of beneficial HDL cholesterol.5 “Our findings suggest that short-sleeping British adults are more likely to be obese, a disease that carries with it many health complications,” the researchers noted.
In this regard, a study published in the journal Sleep found that sleeping longer on weekends (aka “catch-up sleep” (CUS)) had a positive effect on body weight. On average, participants who slept up to two hours longer on weekends than during the week had significantly lower BMIs than those who did not CUS.6 Lack of sleep affects hormone levels, increasing the ‘hunger hormone’ ghrelin and decreasing leptin, which is involved in satiety.
By activating the endocannabinoid system, which is involved in regulating appetite and food intake, sleep deprivation leads to snacking similar to marijuana use. In the featured study, researchers hypothesized that shorter sleep duration might increase unhealthy eating, but in this case, they found no such association.
How Does Sleep Affect Your Waist Circumference?
Sleep is intricately linked to the body’s ability to function properly. When you skimp on sleep, you lose self-control and your willpower to make healthy eating choices. But on a biological level, sleep deprivation also disrupts important hormones and metabolic functions, such as ghrelin and leptin, as mentioned. Losing just 30 minutes of sleep each night disrupts your metabolism and leads to weight gain.
In fact, losing 30 minutes of sleep on a weeknight was associated with a 17% and 39% higher risk of obesity and insulin resistance, respectively, one year later.7 That means that if you consistently sleep only 7 hours out of the required 8 hours of sleep, your risk of obesity increases by about 34%, while your risk of developing insulin resistance, a hallmark of most chronic diseases including type 2 diabetes, also increases by 78%.
Another surprising study found that people who slept only five hours a night gained nearly two pounds a week, mostly by eating more calories late at night. In contrast, people who slept nine hours a night maintained their weight and tended to eat less refined carbohydrates and unhealthy fats.8 These results also apply to children, with the study finding that those who were the most sleep-deprived were 4.2 times more likely to be obese.9
If you’re trying to lose weight, getting enough sleep can make all the difference. A study from the University of Chicago found that dieters who slept 8.5 hours a night lost 55 percent more body fat than dieters who slept 5.5 hours a night.10 “Sleep deprivation may impair the efficacy of typical diets for reducing metabolic risks associated with weight loss,” the researchers wrote, adding:11
“However, when calorie restriction is present, neuroendocrine changes associated with sleep restriction may impair the efficacy of commonly used diets in such individuals who do not have sufficient sleep. For example, higher ghrelin concentrations may help maintain fat, while increased hunger may contribute to compliance with calorie restriction.”
How to Measure If You’re Not Getting Enough Sleep and It’s Putting You at Risk for Your Health
Globally, the average amount of sleep a weekday has decreased by about 37 minutes over the past decade.12 It is estimated that approximately 83.6 million adults in the United States suffer from sleep deprivation.13
In addition to weight gain, sleep deprivation has been linked to type 2 diabetes and metabolic syndrome. The featured study also found that short sleep interferes with thyroid hormones and increases C-reactive protein (CRP) levels, which promotes inflammation and increases the risk of type 2 diabetes.14
In addition to chronic illness, sleep deprivation has the same effect on your immune system as physical stress or illness.15 This explains why sleep deprivation is linked to an increased risk of many chronic and acute diseases, such as colds and flu. In fact, studies have shown that adults who sleep less than six hours a night are four times more likely to catch a cold when directly exposed to a virus than those who sleep at least seven hours.16
Sleeping less than five hours a night increased the risk by 4.5 times. The study found that sleep was more important than any other factor in protecting against cold viruses, including stress levels, age and smoking.
You probably already know if you are sleep deprived or not, but if you are not sure, the late physiologist and sleep researcher Professor Emeritus Nathaniel Kleitman devised one of the simplest tests to determine if you are sleep deprived. As a pioneer in sleep research, he knew this.
Here’s how it works: Take a spoon early in the afternoon and go to a darkened bedroom to take a nap. Place a metal tray on the floor next to your bed, and when you’re about to fall asleep, place the spoon on the tray. Be sure to check the time. Then, when you inevitably fall asleep and the spoon falls onto the tray and wakes you up, immediately check the time again and write down how much time has passed.
According to Kleitman, if you fall asleep within five minutes, you are seriously sleep deprived. If it takes you 10 minutes to fall asleep, that is a sign that you still need more sleep. However, if you were awake for more than 15 minutes before falling asleep, you are probably well rested.17 Even if you don’t have a spoon or metal plate, you can set an alarm for 15 minutes and make sure you don’t fall asleep before the alarm goes off.
Most adults need eight hours of sleep per night.
Sleep needs vary depending on age, activity level, and health, but research clearly shows that eight hours of sleep per night is ideal, and most experts agree. However, keep in mind that eight hours of sleep does not mean eight hours in bed. If you go to bed at 10 p.m. and wake up at 6 a.m., you can say you’ve slept eight hours. In reality, you’ve probably fallen asleep for at least 15 to 30 minutes, and you may have woken up more than once during the night.
But with the advent of fitness trackers, we now have access to actual sleep data (and much more) from wristband users. This data is incredibly useful on a personal level, and can help you decide when to go to bed to get a decent eight hours of sleep. If your sleep problem is not about when to go to bed, but rather what you do after you go to bed, pay attention to your sleep hygiene.
Perhaps the most important natural “trick” for improving sleep is to get adequate exposure to bright light during the day and to avoid blue light at night. In the morning, bright, blue-rich sunlight signals to your body that it is time to wake up. At night, as the sun sets, darkness signals to your body that it is time to sleep.
Ideally, get at least 10 to 15 minutes of natural light as soon as you wake up in the morning to help your circadian rhythm system reset itself. This sends a strong message to your body clock that it’s time for the day, and you’re less likely to be confused by weak light signals later.
Then, around noon, get another 30 minutes of sunlight. An hour or more would be better. If your schedule requires you to wake up before sunrise and get to work, try to get at least 30 minutes of bright sunlight any time during the day.
In the evening, as the sun begins to set, wear amber glasses that block blue light. You can also reduce your exposure to light by dimming your lights and turning off electronic devices, which suppresses melatonin production. Better yet, replace LEDs with incandescent or low-voltage incandescent halogen bulbs. After the sun goes down, you can also replace them with lower-wattage bulbs that emit yellow, orange, or red light if you need some light.
A salt lamp illuminated by a 5-watt bulb is an ideal solution that doesn’t interfere with melatonin production. Candles also work well. If you’ve already optimized your light exposure but are still having trouble sleeping, check out my 33 Healthy Sleep Secrets for a more comprehensive list of strategies for a better night’s rest.
