By Michael Breus, PhD, ABSM
Here’s the flipside to the story about foods that can help you sleep better: eating a diet heavily composed of the “wrong” foods can interfere with your sleep.
That’s the news from a new study conducted by scientists at the University of Minnesota and Minneapolis Veterans’ Affairs Medical Center and presented at the annual meeting of the Society for the Study of Ingestive Behavior. What are the wrong foods in this case? A diet made of up high-fat foods may diminish the quality of your sleep as well as cause you to gain weight.
To investigate the effects of a high-fat diet on sleep, researchers put rats on a fatty-food diet for 8 weeks. The rats, no surprise, gained weight. They then monitored the rats’ 24-hour sleep-wake cycles and found that the animals’ sleep cycles had changed for the worse:
- Rats who ate the high-fat diet for 8 weeks slept more than rats on a regular diet
- These same rats also showed more fragmented sleep
- The extra sleep accrued by the high-fat-diet rats mostly occurred during the daytime.
Researchers likened this daytime sleeping among the high-fat-diet rats to the excessive daytime sleepiness that is common among people who are overweight or obese.
We know a lot—and we’re learning more all the time—about the connections between sleep and weight. How lack of sleep causes hormonal changes in the body that stimulate appetite. How the timing of meals and sleep can affect daily calorie intake: eating late in the day, and the night-owl schedule that often accompanies late-in-the-day calorie consumption, is more likely to lead to weight gain. How sleep can stimulate reward centers in the brain and impair brain function associated with impulse control and judgment. The result? A greater tendency to eat high-fat, high-sugar, often heavily processed foods.
So what’s the connection between a high-fat diet and poor sleep quality? In discussing their results, researchers suggest the link may be a chemical in the brain that’s involved in regulating both sleep and weight: orexin.
Orexin (also known as hypocretin) is a neuro-chemical that plays a critical part in regulating our daily sleep-wake cycle as well as in managing appetite. Here’s some of what we know about the role orexin plays in the connection between sleep and weight:
- Orexin is one of several chemicals in the brain that help govern our 24-hour sleep/wake cycle. In particular, orexin is involved in stimulating wakefulness. A lack of orexin can lead to serious disruptions to daily life: orexin deficiency is believed to be a primary cause of the sleep disorder narcolepsy. People with narcolepsy experience extreme levels of daytime sleepiness and “sleep attacks,” when they may fall asleep abruptly at any time during the day.
- Orexin is active in the hypothalamus region of the brain. Known as the “feeding center,” the hypothalamus is the part of the brain involved in regulating appetite, hunger, and impulse control. Orexin has been shown in studies to be directly involved in the complicated chemical process that creates the urge to eat.
- Researchers who examined mice genetically engineered with orexin deficiency found that these mice were heavier than normal mice, despite being fed a more restrictive diet. Researchers discovered that the mice bred to lack orexin had not developed a special type of fat—brown fat—that actually functions as a fat-burning engine in the body.
- In this study, rats were fed a high-fat diet and gained weight. These rats demonstrated a significant drop in activity levels compared to their levels of physical activity before they started the diet. These rats also showed a decrease in their sensitivity to orexin.
In this latest study, researchers suggest that a similar decrease in orexin sensitivity brought about by weight gain from high-fat foods as the cause of the poor and interrupted sleep that also came about.
We’ll likely see a great deal more research into the role of orexin, and its possible role in influencing both weight and sleep. You already know that a high-fat diet is bad for your waistline, but fat itself is not the enemy. A diet that includes reasonable portions of healthy fats can help keep you healthy and tipping that scale in the right direction. Improving your sleep is another great reason to limit your high-fat food intake and stick primarily to smart fats instead.
Michael J. Breus, PhD
The Sleep Doctor™