Our sleep is influenced by the food we eat. In addition, some types of food are good to eat before bedtime while others are best avoided. Since no studies have addressed the interaction between nutrients/foods and specific parameters of sleep, Australian researchers conducted a study to investigate the link. Their findings were published in 2017 in the Asia Pacific Journal of Clinical Nutrition.
The study involved 784 men between the ages of 35 and 80. Diet was assessed using a food frequency questionnaire that asked participants about their consumption of 167 food items and six alcoholic beverages over the past year using a 10-point frequency scale.
Sleep was assessed subjectively through telephone interviews and questionnaires, and objectively through in-home polysomnography scored by an experienced sleep technician.
Questionnaires also collected data on:
- Marital status
- Work status
- Physical activity
- Chronic disease
Participants were also weighed, their height and waist circumference was measured, blood pressure was taken, and medication use was recorded.
The role of diet on sleep
After analyzing dietary samples, researchers grouped participants into three dietary groups. Group one was characterized by high intake of vegetables, fruits, and legumes. This group was referred to as the "prudent" dietary group. Group two was characterized by high intake of processed meat, snacks, red meat, and takeout foods, and was referred to as the "Western" dietary group. Finally, group three was characterized by those who didn’t fit into either of the previous groups and was referred to as the "mixed" dietary group.
The study found that those in the prudent dietary group tended to be older, lighter, less depressed, more highly educated, consumed less alcohol and fewer cigarettes and were more active than those in the other groups. In addition, those in this dietary group fell asleep faster compared to individuals in the other dietary groups (sleep onset was 16.3 minutes in the prudent dietary pattern group, 19.2 minutes in the Western dietary pattern group, and 22.5 minutes in the mixed pattern group).
After adjusting for age, demographic and lifestyle factors, weight, and chronic disease, the prudent dietary group was associated with a six-minute reduction in the amount of time taken to fall asleep while the mixed pattern group was associated with a four-minute reduction in the amount of time taken to fall asleep.
No associations were found between dietary groups and other sleep measures such as daytime sleepiness, sleep quality, or total sleep duration.
Foods in the prudent dietary group
Individuals in the prudent dietary group tended to consume more of these foods:
- Root vegetables
- Stalk vegetables
- Fruity vegetables (foods that seem like vegetables but are fruits)
- Leafy vegetables
- Potatoes without fat
- High fiber bread
- Citrus fruit
Foods in the Western dietary group
Those in the Western dietary group tended to consume more of the following foods:
- Processed meat
- Red meat
- Takeout foods
- White bread
- Soft drinks
- Pasta and rice
Why does diet affect sleep?
The authors pointed to previous research that found diet may affect sleep architecture by reducing how long it takes to fall asleep and increasing non-rapid eye movement sleep.
A previous study found that meals with a high glycemic index helped healthy young men fall asleep faster compared to low glycemic meals. Root vegetables, which tend to have a high glycemic index, comprised many of the foods found in the prudent dietary group — and this may help explain why individuals in this group tended to fall asleep faster.
The authors of the study also suggested that the anti-inflammatory properties of healthier diets may also influence sleep (disturbed sleep can trigger the body’s immune system and lead to inflammation). Studies have also linked high consumption of fat with an increased frequency of pauses in breathing during the night (which is a symptom of sleep apnea) and reduced sleep duration.
If you’re struggling to fall asleep at night, try consuming a diet rich in vegetables, fruits, and legumes and reduce your consumption of processed meat, red meat, and takeout food. Not only will you be improving your overall dietary health, you could end up improving your sleep health, too.