You know that what you put in your body and how active you are affects your weight, but there’s an important piece of puzzle you may be missing: Sleep.
Recent polls on sleep from Gallup to the National Sleep Foundation have found that Americans — young and old — simply aren’t getting enough zzz’s. Sleep deprivation has been linked to a host of potential health risks in recent studies, including potential impacts on metabolism, food cravings and weight management. If you’ve been eating right and staying active, but putting sleep on the sidelines, it may be time to reprioritize. Here's why:
1. Being tired might cause you to eat more.
Studies have shown that sleep restriction leads to marked decreases in leptin and increases in ghrelin. Leptin is the hormone that suppresses appetite, while ghrelin stimulates appetite. So basically this means that sleep-deprived people feel hungrier and less sated, which could cause them to eat more.
When you’re tired, one of the cognitive side effects that’s been demonstrated in research is impaired decision making. Studies have also found that sleep deprivation actually increases your cravings for calorie-dense, high-carb and junk foods. So, not only are you feeling hungrier due to the ghrelin, your sleepy self is also more inclined to make unhealthy food decisions, like giving into those pizza cravings.
2. Sleeping too little or too much can alter your metabolism.
While you are at rest, your body is hard at work repairing cell and tissue damage and doing other things to keep you healthy. Some of this may relate to insulin and your metabolism.
One recent study from a Doha University looked at the sleep habits of over 500 people recently diagnosed with type-2 diabetes. Researchers found that people with weekday sleep debt were more likely to be obese. At follow-up intervals six and 12 months later, weekday sleep debt was still associated with higher risk of obesity and also insulin resistance. Both risks increased significantly for every additional 30 minutes of sleep debt per day.
Other research has identified links between ongoing partial sleep deprivation and hormonal imbalance, inflammation, changes to the way the body responds to glucose and overstimulation of the sympathetic nervous system. In large studies, increased risk of diabetes has also been demonstrated for both short sleepers (less than 6 hours) and long sleepers (over 8 hours). Potential connections could be related to elevated cortisol levels and changes in growth hormone secretion seen in sleep restriction, which may contribute to the development of insulin resistance.
3. Irregular sleep patterns could lead to weight gain.
One of the core principles of “good sleep hygiene” is sticking to a regular routine and schedule. Normalizing bedtimes and wake-up times tells your body what to expect and helps support your internal clock. Keeping odd hours or drastically varying weekday and weekend schedules could increase risk of sleep problems and may be tied into weight.
Penn State researchers recently looked at over 300 teens’ eating and sleep habits and found that varying sleep times affected eating habits. Variations of an hour or more (either more or less sleep) were associated with eating more calories, more fat and more carbohydrates, as well as increased nighttime snacking.
Another study of college-age women found that inconsistent sleep habits were associated with higher body fat and body mass index (BMI) scores. While bedtime, wake time and overall sleep duration all had an impact, inconsistent wake times were most predictive of higher body fat.
So how much sleep do you need to support weight loss or maintenance? In the range of seven to nine hours, according to a recent large review by the National Sleep Foundation’s panel of experts. The majority of adults need a minimum of seven hours, but you might need more. The key is to find the sweet spot that leaves you feeling well-rested.
Consistency is also important. Try to chose a wake-up time you can stick to within an hour every day of the week, even on the weekends, to support your body’s natural rhythms.
As the growing body of research shows, sleep is quite important to weight in several ways. Placing the same importance on rest that we place an diet and exercise may just be key to achieving fitness and to maintaining long-term health.