The Effects of Sleep Deprivation on Appetite Regulation and Weight
Ironically, while writing this blog post, I have endured one of the most sleep deprived decades of my life! I can say from my firsthand experience as a working mom of three young ones, that a few nights of missed sleep don’t do anything positive for our bodies. Lack of sleep will cause the obvious symptoms of fatigue, moodiness, memory issues (loss) and often times, mindless eating.
When it comes to missing out on adequate zzz’s, it is not shocking to learn that there are more harmful effects on our health than the obvious ones mentioned above! Over the past three decades, the rates of both obesity and sleep deprivation (defined as less than 6 hours per night) have both increased in an alarmingly similar pattern. Obesity prevalence now greater than 35% and according to recent studies, close to 30% of adults in the US sleep less than 6 hours per night. Much of this sleep deprivation can be attributed to the increase in technology- excessive time spent in front of brightly lit screens, access to emails, cell phones and online capabilities at all hours, it seems harder to shut our brains “off” and get the necessary rest our bodies need to stay healthy.
Sleep affects so many different regulatory systems. There are several potential mechanisms by which sleep deprivation affects weight regulation and energy balance.
Hunger and satiety are regulated by metabolic and hormonal signals. Leptin is a facilitator of long-term regulation of energy balance, suppressing food intake and thereby inducing weight loss through the promotion of satiety. In various sleep studies, leptin has been shown to decrease when periods of sleep deprivation exist. Ghrelin on the other hand is a fast-acting hormone, secreted in the stomach whose actions induce hunger. Ghrelin is seen to increase in times of sleep deprivation. Disruption of these appetite regulating hormones due to increased time awake, can lead to increased intake of food and often times, when tired, our bodies crave energy dense foods and quick “pick me ups” that can lead us to crave less than healthful foods. To a lesser extent but nonetheless involved, is Peptide YY, a factor released in the gut following the ingestion of food. When this Peptide YY is decreased due to sleep deprivation, it can also contribute to an increase in appetite.
In addition, this sleep deprivation most often is accompanied by lethargy, which naturally leads to decreased energy output or expenditure. If this becomes a chronic issue, this fatigue can essentially cause a decrease in our resting metabolic rate. In other words, our good intentions to exercise after work may be lost if we’ve suffered a few too many hours of restful sleep.
Glucose production has shown to increase in almost every study conducted on sleep deprivation. In addition to the glucose increase, there is a corresponding decrease in insulin sensitivity. Our fat cells play an important role in insulin processing, including regulating energy use and storage. Fat cells become less receptive to insulin signals after just a few days of sleep deprivation. Insulin has a powerful ability to prevent fat breakdown by its anabolic (rebuilding) properties. Insulin sensitivity describes how recpetive the body is to the effects of insulin, and an insulin sensitive individual will require smaller amounts of insulin to lower their blood glucose levels than someone who has low sensitivity. Low insulin sensitivity can lead to a variety of health problems as the body tries to compensate for having low sensitivity to insulin by producing more insulin.
This extra insulin release results in a high level of circulating insulin in the blood (called hyperinsulinemia) and is associated with damage to the blood vessels, high blood pressure, heart disease, osteoporosis and obesity.
Another major factor to be aware of with lack of adequate sleep is that studies show stress hormone cortisol is also affected. Specifically, there are marked increases in evening concentrations of cortisol. This makes sense because cortisol is a highly contributing factor to our wakefulness. More cortisol, more energy to stay awake. Normally, cortisol is high in the morning and gets lower through the day. It should be lowest at night so you can sleep. Sometimes cortisol levels get flipped upside down so that they’re low in the morning and high at night, meaning you’re tired through the day and then you can’t sleep at night. It’s a vicious cycle because not getting enough sleep increases your cortisol levels the next evening. . High cortisol levels alone can cause weight gain especially in your belly region.
Ideal amounts of sleep are variable based on a variety of factors, age being a big one. Some general guidelines for number of hours per day to aim for are: Infants 12-15; Teenagers 8.5-9.5 and Adults 7-9.