Feeling sleepy during the day? If you stayed up late working on the computer or watching a late night movie, you can blame it on that but for some people feeling sleeping and tired during the day is a recurring theme. They regularly find themselves nodding off at work or simply lack the motivation to get things done. If that sounds like you, you might want to take a closer look at your diet. A new study shows that what you eat plays a role in how energetic and alert you feel during the day.
Diet and Daytime Fatigue
According to a new study published in the journal Sleep, eating a diet high in fat is linked with daytime sleepiness and lack of energy. Researchers asked a group of healthy men and women to spend 4 nights in a sleep lab while using a test to measure their level of sleepiness. They also monitored the composition of their diet during the 4-day study. Unlike previous studies that looked at subjective levels of sleepiness, this study used physiological measures to assess levels of fatigue and sleepiness thereby providing more objective measures of sleepiness.
Did diet have an impact? Participants who ate a high-fat diet had greater levels of sleepiness and fatigue compared to those who ate a diet higher in carbohydrates. Interestingly, protein wasn’t linked with how sleepy participants felt. Based on this study, started the day with a greasy sausage, egg and cheese biscuit wouldn’t be the best choice if you want to be alert and energetic all day.
Although this study showed a diet higher in carbs was better for reducing fatigue and sleepiness, not all carbs are the same. High-glycemic carbs are rapidly absorbed, sending your blood sugar and insulin on a roller coaster ride. This gives you a temporary rush of energy followed by fatigue a few hours later. The key is to choose fiber-rich carbs that are absorbed slowly and add lean protein to a meal to further reduce the glycemic response.
How much you eat is another factor. Eating a big lunch might sound like a good idea since you’re giving your body a lot of fuel but too much isn’t always better. The portion of your brain called the hypothalamus has neurons that are sensitive to the amount of glucose in your bloodstream. When you eat a meal and your blood glucose level rises – these neurons turn down the production of orexin, a hormone that regulates appetite and your sleep-wake cycle. Orexin levels drop after you eat a big meal so you feel sluggish and less alert.
After several hours of fasting as glucose levels drop, orexin levels begin to rise again and you feel hungry and motivated to eat. How many times have you felt sleepy after overeating? That’s partially because it triggers a rapid rise in blood sugar and a drop in orexin. Orexin plays a big role in how energetic you feel. When levels of orexin drop, you feel like curling up and taking a nap rather than getting things done.
High-Fat Diets May Hinder Sleep as Well
Why does a high-fat diet cause daytime sleepiness? In animal studies, a diet high in fat reduced sleep quality in rats and was linked with more fragmented sleep with frequent nighttime awakenings. Plus, when the rats ate a high-fat diet, they were less active during daytime hours, similar to the daytime fatigue and feeling sleepy that humans experience. Scientists believe a diet high in fat reduces sensitivity to orexin. This causes you to feel more sluggish and less energetic during the day and disrupts your sleep-wake cycle so you don’t sleep as well at night. This can cause you to feel tired and less motivated when you’re awake.
The Take-Home Message
To feel more energetic and alert during the day, eat smaller meals made up of fiber-rich carbs that are slowly absorbed with a lean source of protein. Limit the amount of fat you eat at a meal if you’re prone towards daytime sleepiness. Snacks like candy bars, cookies and desserts are a double whammy because they’re high in fat and contain rapidly absorbed carbs.
Don’t forget about breakfast. That’s not a meal you want to skip since you’ve just completed an overnight fast. Make it a high-fiber one. A study published in the Journal of Food Sciences and Nutrition showed that starting the day with a breakfast high in fiber-rich carbs boosted daytime alertness more than one high in fat. More evidence that fat can make you feel sleepy. How about a bowl of hot oatmeal or quinoa with fruit and nuts to start your day? You’ll be getting a healthy dose of fiber and slowly-absorbed carbohydrates to keep you running on all cylinders until lunch.
References:
Medical News Today. “Diet Linked with Daytime Sleepiness and Alertness in Healthy Adults”
J Physiol. 2011 Dec 1;589(Pt 23):5701-8.
Science Daily. “Weight Gain Induced by High-Fat Diet Increases Active-Period Sleep and Sleep Fragmentation”
WebMD. “Fatigue Fighters”
