What Role Does Diet Play in Sleep Quality?

September 15, 2019

by Cathe Friedrich

It’s a hidden epidemic! According to the National Sleep Foundation, two out of three adults get less than the recommended eight hours of sleep per night. Now, with the popularity of smartphones and other devices that expose the eyes to blue light at night, the number of people who don’t sleep enough or who suffer from poor sleep quality is likely to grow.

Even adults who lie in bed for eight hours may have interrupted and non-restorative sleep. No wonder so many people are dragging around with eyes half shut these days! Sleep is vital for healthy brain function. Plus, poor quality sleep is linked with other health problems, including cardiovascular disease, type 2 diabetes, and obesity.

If health concerns don’t motivate you to sleep more, how about the issue of belly fat? A study found that sleeping less than 5 hours nightly was correlated with an increase in belly fat in younger people. Not to mention, you won’t function as well or feel your best if you skimp on sleep.

Since diet plays a key role in almost everything we do, you might wonder how what you eat impacts the quality of your sleep. We know that drinking too much caffeine, especially later in the day, can interrupt sleep, especially for people who metabolize caffeine slowly. Caffeine can stay in your system for up to 7 6 hours. But what about other foods? Let’s look more closely at each macronutrient and the effect it has on sleep.

Dietary Fat

Some studies link higher consumption of saturated fat with reduced sleep quality. The NHANES study that began in 2007 used sleep surveys found that consuming more of certain saturated fatty acids was correlated with poor sleep quality. One is hexadecanoic acid, found in dairy, meat, and hexanoic acid in coconut oil is linked with problems falling asleep and staying asleep. In contrast, other studies show consuming more polyunsaturated and monounsaturated fats is associated with better sleep quality. So, it may be a question of choosing your fats if you want better sleep. These studies are correlational, but a number of studies suggest the type of fat you eat impacts sleep quality. Based on this data, limit saturated fat and choose more polyunsaturated and monounsaturated fats.

Protein

In contrast to saturated fat, some studies link a diet high in protein with significant improvement in sleep quality. One study found that higher doses of the amino acid tryptophan improved sleep quality. Individuals reported falling asleep more quickly and waking up less. This study holds some weight since it was a controlled study that measured sleep with a wrist actimeter. These findings aren’t surprising since tryptophan is a precursor to the neurotransmitter serotonin, a brain chemical linked with mood, and melatonin, the so-called sleep hormone. Your body can’t make tryptophan, so you have to get it through diet. On the other hand, some studies fail to show that a diet higher in protein and tryptophan improves sleep.

Carbohydrates

With regard to how carbohydrates affect sleep quality, study results are all over the place. Some studies suggest that consuming high-glycemic carbs 4 hours before sleep shortens the time it takes to fall asleep. Other studies suggest that low-carbohydrate diets have an advantage and lead to better sleep quality. A study published in the Journal of Clinical Sleep Medicine found that consuming more sugar, more saturated fat, and less fiber throughout the day was associated with more nighttime awakenings and lower quality sleep.

Since we know high-glycemic carbs and sugar lack nutritional benefits and can negatively impact blood glucose, it’s best to eliminate those for health reasons, regardless of their impact on sleep. Choose more nutrient-dense, fiber-rich carbs instead. High-glycemic carbs can cause blood sugar fluctuations that could trigger awakenings during the night in some people.

The Role of Micronutrients in Sleep Quality

Micronutrients, like vitamins and minerals, don’t supply your body with energy, but they’re critical for health. Some studies link low levels of vitamin D with sleep problems. In fact, a study published in the journal Nutrients found that a vitamin D level below 20 ng/ml, a level that indicates a deficiency, was associated with sleep disorders. Other studies support this finding. Another reason to check your vitamin D level if you can’t sleep!

Be sure you’re consuming a mineral-rich diet. One study found that consuming less magnesium, iron, zinc, selenium, and phosphorus, was correlated with shorter periods of sleep. Based on other literature, magnesium may be very important for sleep as it has a calming effect. One study found that nursing home residents who supplemented with zinc, melatonin, and magnesium enjoyed more sleep and a better quality of life.

Other Ways to Improve Sleep Quality Through Diet

Watch the nighttime eating. If possible, avoid snacking after dinner. Your body has internal rhythms called circadian rhythms that direct hormones, including those involved in sleep. You want your body to transition into sleep mode after dinner. Snacking can interfere with this transition.

If you need a snack, consider sipping a cup of caffeine-free chamomile tea. Chamomile tea contains apigenin, an anti-inflammatory compound that binds to receptors in the brain that reduce anxiety. Also, avoid eating a large dinner or foods that increase the risk of heartburn or indigestion such as hot, spicy foods.

The Bottom Line

Overall, the best evidence suggests that limiting saturated fat, sugar, and caffeine and consuming foods higher in polyunsaturated fats and high-fiber carbs benefit sleep quality. However, studies are somewhat conflicting. Make sure the foods you choose are nutrient-dense as getting enough of certain minerals, particularly magnesium and zinc, may help with sleep quality. Also, try to make your biggest meal early in the day and lighten up on dinner to allow your body to better prep for sleep.

References:

· Nuatraceuticals and Functional Foods in Human Health and Disease Prevention. CRC Press. (2016)

· National Sleep Foundation. “Sleep Linked to Gains in Belly Fat”

· J Clin Sleep Med. 2016 Jan 15; 12(1): 19–24.

· Nutrients. 2018 Oct; 10(10): 1395.

· PLoS One. 2017 Jul 7;12(7):e0180901. doi: 10.1371/journal.pone.0180901. eCollection 2017.

· J Am Geriatr Soc. 2011 Jan;59(1):82-90. doi: 10.1111/j.1532-5415.2010.03232.x.

· Mol Med Report. 2010 Nov 1; 3(6): 895–901.doi: 10.3892/mmr.2010.377.

· WebMD.com. “Doze Control: Eat Right and You’ll Sleep Like a Baby”