This past year has been tough on our wellbeing. It’s pretty much accepted that the pandemic has stolen our sleep, with one in four people now reporting disturbed nights. But now we are also waking up to our ‘lockdown pounds’ (or ‘self-isolating stones’, for the particularly sourdoughed among us). Could there be a connection between insomnia and a diet packed with comfort food?
Most of the chat around ‘coronasomnia’ has been about emotional issues such as stress and anxiety. But it’s been known for a while that our diet can also affect our sleep patterns (and vice versa). Marie-Pierre Saint-Onge is associate professor of nutritional medicine in the Department of Medicine and Institute of Human Nutrition at Columbia University Medical Center in New York. “The pandemic has had mixed effects on diet and physical activity,” she says.
“Yes, there have been some improvements – more home cooking, and an increase in fresh produce, for example,” she says. “But there have also been negative changes. Alterations to eating patterns and stress eating could be contributing to poor sleep, as might a deterioration in lifestyle habits and an increase in comfort food and alcohol.”
In 2016, Saint-Onge was the lead author of a study published in the Journal of Clinical Sleep Medicine, which found eating greater amounts of fibre predicted more time spent in the stage of deep, slow wave sleep. In contrast, a higher percentage of energy from saturated fat (found in butter, cakes, biscuits and processed meats) predicted less slow wave sleep, indicative of less restorative sleep.
“It was most surprising that even a single day of greater fat intake and lower fibre could influence sleep parameters,” she says.
The study also found that participants fell asleep faster after eating fixed meals provided by a nutritionist, which were lower in saturated fat and higher in protein than self-selected meals. It took participants an average of 29 minutes to fall asleep after consuming foods and beverages of their choice, but only 17 minutes to fall asleep after eating controlled meals.
Those who consumed more sugar were also seen to take longer to fall asleep, as well as more likely to wake up during the night. “Eating sugary foods – and the additional body fat that typically comes from a high-sugar diet – reduces the effectiveness of hunger-suppressing and metabolism-regulating hormones, including leptin and ghrelin,” says clinical psychologist Michael Breus, aka thesleepdoctor.co.uk. “Cravings, and an appetite distorted by over-consumption of sugar, lead to late-night eating that will disrupt your sleep.
“That poor sleep in turn makes our sugar cravings even worse: a wealth of studies show that poor quality and insufficient sleep interfere with the normal production and function of appetite-regulating hormones including leptin and ghrelin,” he adds. Thus, exhausted, we crave refined carbohydrates such as sugary snacks. And on it goes.
Conversely, some specific foods are seen as helpful for sleep. Melatonin is a natural hormone produced by the pineal gland in the brain, which helps control the sleep cycle. It can be taken synthetically (as a dietary supplement) but is also found in various food groups, including mushrooms, egg and fish. A 2017 review in the journal Nutrients showed that ‘melatonin concentration in human serum can significantly increase after the consumption of melatonin-containing food.’ The study mentioned cereals, germinated legumes (bean sprouts or quinoa) and seeds as good dietary sources of melatonin.
Some of the ‘lay’ diet literature reports that a diet high in the amino acid L-tryptophan (found in turkey, chicken, cheese, yogurt and fish) affect levels of the ‘feel good hormone’ serotonin, which then creates melatonin and can lead to sounder sleep. Although partly true, this is not the complete story. “Proteins high in tryptophan require assistance from foods high in carbohydrates to help tryptophan reach the brain and affect serotonin and melatonin levels,” says St-Onge. “Tryptophan competes with other amino acids to get to the brain. Sadly, focusing solely on eating more tryptophan may not be helpful.”
Certain fruits can help too. In one four-week study, 24 adults ate two kiwi fruits an hour before going to bed, fell asleep 42 per cent more quickly, and their total sleep time increased by 13 per cent. But this was obviously a small study. The combination of omega-3 fatty acids in fish such as salmon and tuna have also been known to increase the production of serotonin, and enhance sleep quality.
When you eat is also important. “Have your dinner at least two to three hours before you go to bed,” says St-Onge. “If you get hungry, have an easy digestible snack such as Greek yoghurt, cereal with milk, or some fruit. But the key thing is to eat fibre all through the day, not just with your evening meal.”
It’s well known that caffeine can interrupt sleep – your last cup of coffee should be six hours before bedtime, according to several studies. Interestingly, a shot of espresso has less caffeine (64mg) than even an 8oz cup of cappuccino. Alcohol might help you fall asleep, but as your liver enzymes metabolise the alcohol during the night and the blood alcohol level decreases, you'd be more likely to experience sleep disruptions and a decrease in sleep quality.
Fizzy drinks are also bad news for sleep. Research from The Lancet published in January 2021 revealed that of 175,261 adolescents who had more than three carbonated drinks a day, they had over 50 per cent higher odds of reporting sleep disturbances.
“The finding that diet can influence sleep has tremendous health implications, given the increasing recognition of the role of sleep in the development of chronic disorders such as hypertension, diabetes and cardiovascular disease,” says St-Onge.
Now the evenings are getting lighter and alfresco dining is back, here’s to a better diet, and sounder sleep.
The Insomnia Diaries : How I Learned to Sleep Again (foreword by Dr Sophie Bostock) by Miranda Levy is published by Aster on June 10. Buy it from Telegraph Books for £9.99 or call 0844 851 1514