Can diet impact sleep?
There are lots of things which can determine whether we get a good night’s sleep or not, like avoiding screens or taking a hot bath, but could what we eat also impact our sleep? We asked 7 experts in nutrition and sleep research, ‘Can diet impact sleep?’, here is what they said…
Can diet impact sleep?
5 out of 7 experts say ‘Yes’
Does diet impact sleep?
5 out of 7 experts answered ‘yes’. Professor Gary Wittert, an endocrinology and nutrition expert from Adelaide University in Australia, says “The answer is unequivocally yes, and confirmed in a number of studies over the past few years.”
Mr Ludovico Messineo, a sleep expert from Flinders University in Australia, is not completely convinced. He says “A healthy diet may help preventing risk factors for a worsened sleep quality (i.e. obesity), however the evidence that a specific diet can impact sleep are scarce.” He goes on to say that “High carbohydrate and high fatty acid intakes might have a slight effect on REM (Rapid Active Movement, the sleep stage where we dream) and slow-wave sleep (the deepest stage): however, results are conflicting and not consistent between the sleep stages.”
What is the evidence that diet impacts sleep?
Some of the disagreement between experts could be due to the challenges that face researchers who study the potential impact of diet on sleep.
Two types of studies which are often used are epidemiological (simply collecting sleep data on people who have different diets) or interventional (asking volunteers to eat a specific diet and then monitoring their sleep). These methods have different advantages and limitations. For example, epidemiological studies may include other factors that haven’t been controlled (e.g. people who eat a certain diet may also live in a particular place or have other factors that might influence their sleep quality). Interventional studies are often limited by their cost and duration.
Dr Marie-Pierre St-Onge, an expert in nutrition and sleep research from Columbia University in the USA, says “There are multiple studies showing an association between diet and sleep. These population, or epidemiological, studies cannot provide information on directionality or causality but do provide interesting data suggesting that diet and sleep are related.” She also says “intervention studies provide some evidence that certain foods can influence sleep. However, in-depth studies that could provide information on causality are needed.”
Dr Ian Walshe, an expert in exercise science and sleep research from Northumbria University in the UK, adds that “Some studies have shown that changes in food intake can alter some aspects of sleep (time taken to fall asleep, amount of time in deep sleep etc). However, these studies are often short term (less than 2 weeks). It is not clear if these results would be replicated when examined long term.”
What food types impact sleep the most?
There doesn’t seem to be a ‘best diet’ for sleep, instead adequate nutrition and avoiding too many unhealthy foods seems to be the best approach.
Professor Wittert says “The type of food choices you make can impact sleep. Eating a diet that is high in processed foods particularly when combined with fat, and limited in vegetables, salad items, whole grain and fruit is associated with poorer quality sleep and greater daytime sleepiness the following day.”
Can drinks affect sleep?
Alcohol and caffeine significantly impact sleep. Professor Wittert says “although people may think alcohol makes them sleep better, even a small amount profoundly disrupts the normal processes of sleep. Caffeine (which is present in tea, as well as coffee and cola drinks) interferes with sleep, partly because of promoting wakefulness and partly due to stimulating the need to get up and pass urine.”
Not all drinks affect sleep though, Mr Messineo says “Specific aliments (i.e. chamomile, milk) are unlikely to have a beneficial effect on sleep, many reports say.”
Does it matter when you eat?
An added complication is that it is not only what we eat and drink, but when we eat that can affect our sleep. Professor Wittert says “Another factor to consider is the timing of food intake - eating late at night and very large meals close to bedtime also disrupt sleep.”
Eating a healthy diet and not having meals too close to bedtime can improve your sleep.
May the facts be with you!
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