Sleep is one of biology’s greatest mysteries. Our understanding of its exact function is poor, but we do know that sleep is extremely important: total sleep deprivation is eventually fatal, while lack of sleep is associated with a shorter lifespan and increased risk of a wide range of diseases.
7 to 8 hours is considered to be the ideal amount of sleep per night, however, there is more to a good night’s sleep than a strict bedtime routine. What we eat and when we eat it has an important impact on sleep quality, because the metabolic changes that occur following a meal conflict with those that occur during sleep.
This sleep state, in which bodily functions slow and brain activity changes substantially, is characterised by changes in a range of hormones. These include the stress hormone cortisol, leptin and ghrelin (which regulate hunger),and serotonin (which regulate circadian rhythm) and . All of these hormones are affected by diet – activity of the digestive system can essentially shift the body to a more active state when it should be slowing down.
How is this to be avoided? One approach is to avoid eating too late in the day. According to Dr. Charles Czeisler from Division of Sleep and Circadian Disorders at Harvard Medical School, studies suggest that there are benefits to time-restricted eating:
Restricted eating recognizes the importance of circadian rhythms. The study concludes that food intake for the day should occur within a 10-hour window, with the first meal of the day taken an hour or more after habitual wake time and the last meal of the day finished three to four hours from bedtime.
For the same reasons, it may be preferable to eat a nutrient-dense lunch and a light supper, rather than the other way around. Dr. Czeisler also warns against drinking alcohol or caffeinated drinks too close to bedtime:
Caffeine has a six- to nine-hour half-life that can delay circadian rhythms and increase next-day sleepiness,” Dr. Czeisler said. “Every glass of wine and every shot of liquor takes two hours for the liver to metabolize, and that disrupts your ability to maintain consolidated sleep.
How to Eat if You Want Better Sleep: https://www.wsj.com/articles/how-to-eat-if-you-want-better-sleep-11585138783
The Global Problem of Insufficient Sleep and Its Serious Public Health Implications: doi: 10.3390/healthcare7010001