"Cheese, and dairy products in general, contain tryptophan, which is converted into serotonin, and serotonin is later converted into melatonin, which is one of our major sleep hormones." Photo / 123RF
Research suggests that eating foods rich in dietary tryptophan and melatonin can improve the quality of our rest.
Many of us have childhood memories of a milky drink just before bed, and there has always been a belief that certain foods will help us nod off more easily and sleep more soundly.
For sleep expert Dr Sophie Bostock, the reality is a little more complex. “Rather than consuming a specific food, the balance of evidence would move towards maintaining a healthy, balanced diet to support our gut microbiome,” she says.
Sleep experts tend to recommend the Mediterranean-style diet, which is high in the essential amino acid tryptophan, from which melatonin – the “sleep hormone” that regulates our circadian rhythms – is synthesised by the body.
Research suggests that eating foods that are rich in dietary tryptophan and melatonin can improve sleep quality, though clinical trials are needed to establish a causal link, says BANT-registered nutritionist Clarissa Lenherr.
While the jury is out on whether specific foods actively promote better sleep, both Bostock and Lenherr advise trial and error to see what works for you.
“For most people, it’s not as simple as, ‘Eat two kiwi[fruit] before bed, and you will enjoy nine hours of deep sleep,’” says Lenherr. “But they certainly won’t do you any harm, and they might help.”
Here, the experts assess the foods and drinks that could help you drift off and improve your sleep quality.
Studies suggest that drinking tart cherry juice, which contains tryptophan and melatonin, can help reduce the severity of insomnia. “When people talk about the foods that might support better sleep, this is the most popular,” says Lenherr.
“There have been a few small studies carried out that suggest that it can improve sleep duration and efficiency, probably because tart cherries are one of the most abundant dietary sources of melatonin."
However, Lenherr points out that in order to ingest the same amount of melatonin found in a supplement, you would need to consume a very large amount.
But it’s not all bad news. “It’s worth bearing in mind that tart cherry juice has other benefits,” Lenherr says. “It’s full of vitamin C and other antioxidants. With our clients who want to trial it, we advise drinking a small glass in the evening.
“The downside, apart from it being quite expensive and not that easy to get hold of, is that – like any fruit juice – it’s a natural source of sugars. If you drink a large glass of cherry juice an hour before bed, that could cause disruption to blood sugar levels.”
The average serving should be around 150ml.
Bostock, too, is intrigued by cherry juice. “The amount of melatonin from even a 200ml twice-a-day dosage of tart cherry juice is a tiny fraction of what would normally be considered a physiological dose or a clinical dose,” she says. “So scientists suspect that it is not the melatonin from tart cherry juice that is beneficial to sleep quality. It may well be something else in it, but we don’t know exactly what.”
Studies have shown that eating two medium-sized kiwifruit an hour before bedtime for four weeks showed promising results in a small group of people with sleep problems. They reported reduced sleep disturbances, along with better sleep quality and sleep duration.
Bostock describes these findings as “promising”, adding: “At present we’re missing a placebo-randomised controlled trial, but in the meantime, kiwis are pretty good for us. And tasty.”
She stresses, however, that the picture is “not really clear”, noting that those sleep improvements were seen in people who were already struggling with their sleep, so the fruit may contain something that corrected an imbalance.
“But it’s certainly true,” she says, “that kiwis contain a lot of chemicals [such as folate, tryptophan and melatonin] that could help us sleep, so it’s worth experimenting to see if they work for you.”
In her practice, Lenherr also advises people with sleep difficulties to try out kiwifruit. “They’re full of fibre and great for your digestive system. They contain melatonin, folate, antioxidants, serotonin precursors – but less natural sugar than a glass of cherry juice. They’re also easy to find and affordable. So, for me, with all those benefits, kiwi is probably number one on my list.”
“Cheese, and dairy products in general, contain tryptophan, which is converted into serotonin, and serotonin is later converted into melatonin, which is one of our major sleep hormones,” explains Lenherr. “Eating a slice of cheddar or some yogurt before bed isn’t going to knock you out like a sleeping pill, but it might help to boost your tryptophan a little and therefore support sleep.”
Lenherr goes on to explain that, ideally, tryptophan-rich foods like cheese should be consumed together with a high-fibre complex carbohydrate. This allows it to be digested properly and make its way to the brain, from where it can improve sleep.
“That combination helps the tryptophan cross your blood/brain barrier. So if you get hungry an hour before bedtime, a little bit of cheese with some wholegrain crackers or some yogurt with oats could be a good option.”
Eating a square of dark chocolate in the lead-up to bedtime has become a popular sleep hack. It’s a good source of magnesium, which is believed to help us enjoy a better night’s sleep by reducing the stress hormone cortisol.
Magnesium deficiency is relatively common in the UK, despite its presence in foods like leafy greens, legumes, nuts and wholegrains. “In large population studies, people deficient in certain vitamins and minerals are often the poorest sleepers. But that doesn’t necessarily mean deficiency causes the problem,” says Bostock.
Anecdotally, many report that taking magnesium improves sleep. Magnesium is a vital mineral, and plays numerous roles in the body. One reason it may affect sleep is its link with stress: people under chronic stress often struggle to absorb enough magnesium from their diet. If you are deficient, there is some evidence that supplementation can improve sleep quality.
However, results are not immediate. “It will probably take seven to 14 days before you notice benefits,” explains Bostock. “Many people claim they feel the effects straight away, but that’s more likely to be the placebo effect.”
While Lenherr agrees that dark chocolate is a great source of magnesium, she insists it’s “not for everyone”, as it contains caffeine. “For people who are sensitive to caffeine, having two squares of dark chocolate after dinner could have a detrimental effect on their sleep. It’s really down to individual sensitivity.”
“The appeal of turkey as an evening snack is down to the fact that it’s a source of tryptophan,” says Lenherr. “But portion size is crucial. If you eat a few small slices of turkey a few hours before bed, you’ll probably digest that quite well, and some of the tryptophan might potentially start activating. But if you eat a Christmas Day serving, all that protein will delay your gastric emptying, which could lead to heaviness and reflux, while also increasing your body’s heat generation as you break it down.”
Have a couple of slices on top of a slice of wholegrain toast or cracker, as the carbohydrates will help the tryptophan make its way to the brain.
Like cheese, warm milk contains high levels of tryptophan, which could explain why hot chocolate and Milo have become bedtime staples.
“Malted drinks like Horlicks also contain natural carbohydrate sources that can help facilitate that tryptophan transport,” says Lenherr.
“But bear in mind that hot chocolate and certain Horlicks drinks are quite high in sugar. Overall, though, I think it’s mainly down to the ritual – that warming, soothing sensation that comforts and calms your digestive system.”
Bostock also highlights the importance of bedtime rituals. “If you’ve got a strong association, perhaps from childhood, that Horlicks will help you wind down before bed, that can be very beneficial. If your body and brain are getting a message – ‘We have warm milk, we fall asleep,’ – it’s deeply reassuring.
“I talk a lot about creating a sense of predictability and familiarity before bedtime. The more we do that for our brains, the more relaxed we feel. Ultimately, we need to feel safe in order to get into, and stay in, a deep sleep.”
Prioritise sleep hygiene
Stress management and sleep hygiene are the cornerstones of good sleep, Lenherr says. “In order to sleep, your body needs dark, quiet and calm, so avoid strong light and try not to watch scary TV shows, as they hype up your nervous system.”
Keep to a routine
“Going to bed and waking up at the same time will help sync your circadian rhythm,” says Bostock. “If you wake at the same time every morning, about 15 hours later your brain will start producing the melatonin that’s going to help prepare you for bed.
“Food is another ‘zeitgeber’ – the cues that tell your body it’s time to be alert. Stopping eating two hours before you get into bed is going to help improve the quality of your sleep.”
Exercise regularly – ideally in daylight
“Daylight exposure is vital for regulating your circadian rhythm,” says Lenherr, “so make sure you get some natural light in your eyes, ideally in the first half of the day. Exercise is beneficial for sleep, but avoid anything too strenuous in the hours before bed, as it can increase your stress hormones.”
Drink herbal tea
Sleepy teas and chamomile are a great way to kick off your sleep routine, says Bostock. “Do your own experiments. They’re warming and soothing, and as long as they don’t contain caffeine or too much sugar, if you think they’re benefiting you, they probably are.”
Take a hot bath or shower
“Not only does having a bath or shower relax our muscles (and keep us off our devices), it also sends more blood flow to the extremities,” says Bostock. “When we step out, our core body temperature drops quickly – a signal for sleep.”