On average, adults need seven to nine hours sleep a night, but many struggle to get anything like that. It’s estimated that around a third of the general population and nearly 50 per cent of older adults suffer from sleep disorders – difficulty getting to sleep, early waking or feeling unrefreshed on waking – and the numbers are rising because of our increasingly stressful lifestyles and a progressively aging population.
Insomnia – what are the causes and how to combat it?
Insomnia can be either an unsatisfactory quantity of sleep or poor quality sleep. Common causes include: stress, anxiety, depression, noise, feeling too hot, cold, or uncomfortable, alcohol, caffeine, nicotine, recreational drugs like cocaine or ecstasy, jet lag and shift work. It’s also a common symptom of the menopause and can be a problem in the years leading up to it – the perimenopause.
We know the general advice: take regular exercise, go to bed and rise at the same time each day, don’t eat a big meal late at night, don’t smoke or drink alcohol, tea or coffee at least six hours before you go to bed, don’t exercise during the four hours before bed, wind down by taking a bath or reading a book, make sure your bedroom is dark, quiet and your bed is comfortable, avoid daytime napping and try not to sleep in after a bad night’s sleep.
Watching TV or using electronic devices late at night can stop you feeling sleepy as computer screens, tablets, smartphones, flat-screen TVs and LED lighting all emit ‘blue light,’ which is especially potent at reducing melatonin production. Scientists refer to the effect this has on teens as ‘social jet lag’.
But what if you’ve tried all these things and still can’t sleep? Are there any foods that can help? To answer this, we first need to understand a little more about the sleep process.
The sleep hormone melatonin
Melatonin regulates your sleep-wake cycles (circadian rhythm) with production rising at night then falling in the day. To produce melatonin, the body needs vitamin B6 and the amino acid tryptophan. Production in the brain is triggered by light signals entering the eye and studies show that a tryptophan-rich breakfast, coupled with daytime exposure to bright light, boosts melatonin, with peak production occurring around midnight in most people.
Vitamin B6 is found in nutritional yeast, muesli, avocados, wheat germ, quinoa, acorn squash, banana, sunflower and sesame seeds, tahini (sesame seed paste), corn on the cob, wholemeal spaghetti, Brussel’s sprouts, spring greens, pistachios, chestnuts, hazelnuts, walnuts, tomatoes and oranges.
Tryptophan is found in soya beans (tofu and tempeh), chick peas, quinoa, buckwheat, oats, chocolate, dried dates, sunflower, sesame and pumpkin seeds, almonds and peanuts. So a tryptophan-rich breakfast could be scrambled tofu or tempeh on toast, chick pea and mixed seed pâté on toast, quinoa or buckwheat porridge with cocoa and/or dates or almond butter on toast.
It’s been suggested that it’s the tryptophan in turkey that leaves people feeling sleepy after their Christmas lunch. However, it’s more likely to be down to overindulgence as turkey isn’t exceptionally high in tryptophan. Soya beans contain more so you’re better off reaching for a slice of Tofurkey!
Disrupted melatonin production can be a problem for shift workers who feel sleepy at night when they are working and can’t sleep in the day. Melatonin supplements may help improve sleep after a night shift, but more trials are needed. The evidence that melatonin supplements can help combat jet lag by resetting the sleep-wake cycle is stronger but you have to time it right!
The power of antioxidants
Melatonin is also an antioxidant – a free radical scavenger that goes around the body mopping up harmful molecules called free radicals that are hell-bent on destruction. It binds to toxic metals such as cadmium and arsenic and prevents them from forming free radicals. It also helps produce more antioxidants, can protect against heart disease and stroke and may help combat diabetes, obesity and cancer. It may also have anti-aging properties.
Melatonin is found in many foods and as production declines with age, increasing dietary consumption could help if you’re struggling to sleep. Good wholegrain sources include wheat, barley, oats and coloured varieties of rice – especially black rice.
The cherry on top
Among fruits, cherries, grapes and strawberries contain the highest levels. Studies show that tart cherries and cherry juice can help increase total sleep time and quality. Given the high concentrations of bioactive compounds in cherries, it’s not surprising that they’re so good for us. Studies suggest that they may reduce the risk of several chronic inflammatory diseases including, arthritis, heart disease and stroke, diabetes and cancer.
Another study found that two kiwi fruits one hour before bedtime significantly improved sleep quality. Kiwis have a high serotonin content but unlike melatonin, serotonin doesn’t cross the blood brain barrier so the mechanism is uncertain. They are a rich source of antioxidants, folate and vitamin C so these may be helping. Plenty of other fruit and vegetables contain these!
Tomatoes and peppers are among the best vegetable sources while potatoes and beetroot provide very little. The melatonin content of tomatoes may be one of the reasons the Mediterranean diet is so healthy. Mushrooms are also a high-melatonin food while pulses and seeds also provide a good source – mung beans, soya beans and mustard seeds. Germinating them can increase the content by as much as 400 per cent.
Among the various nuts, pistachios have the highest content but almonds and walnuts are good, too. Nuts contain many other vitamins, minerals and fibre and walnuts are a great source of healthy omega-3 fats. A small 28 gram handful of nuts is an adequate portion.
Sufficient magnesium in the diet is essential too if you are going to get a good night’s sleep. This important mineral interacts with the brain chemicals responsible for reducing anxiety, promoting relaxation and preparing our bodies for sleep. Low levels have also been linked to night-time leg cramps!
Good sources of magnesium include wholegrain foods (quinoa, wholewheat spaghetti, wholegrain rice, oats and wheat germ), nuts (Brazil nuts, almonds, cashews, hazelnuts, walnuts, pecans, pistachios, peanuts and peanut butter), seeds (pumpkin, sunflower and sesame seeds and tahini – sesame seed paste) pulses (tofu, baked beans, soya beans, edamame and lentils), spinach, molasses – black treacle, soya milk and cocoa powder.
Animal foods and melatonin
Animal foods, especially eggs and fish, contain melatonin but they also contain unhealthy cholesterol, saturated fat, hormones and animal protein. All the world’s oceans are polluted with toxic chemicals so fish have the additional problem of being contaminated with persistent organic pollutants (POPs) like polychlorinated biphenyls (PCBs) and dioxins as well as mercury. You are better of scoffing a small handful of pistachios and cherries!
It’s a popular misconception that warm milky drinks help children sleep. Researchers from University College London compiled the largest record of dietary information for young children in the UK and found that night-time milk drinks contributed to short sleepers (who had both a later bedtime and an earlier wake time) consuming more energy, potentially contributing to later weight gain. They concluded that feeding at night doesn’t help young children sleep.
Don’t confuse tiredness with hunger
Poor sleep is strongly linked to weight gain in adults, too. Studies show that adult short sleepers – who sleep less than seven hours a night – have higher calorie intakes, notably from fat and snacks, than do normal sleepers. It could be that when staying up late, it’s easy to confuse tiredness with hunger. If you’re going to have a snack in the evening, keep it small and combine complex carbohydrates with a high-protein food like oatcakes and nut butter.
There is some evidence that drinking chamomile and passionflower teas may improve sleep quality. The calming effect may be due to antioxidants found in both teas binding to certain receptors in the brain that promote sleep. However, more research is needed. Sprinkling lavender oil on your pillow might help – if it relaxes you, sleep may come easier.
For women experiencing the menopause, plant hormones called phytoestrogens, and found in soya, have been show to help. Hormone replacement therapy (HRT) may also help if problems persist. Most HRT in the UK and Europe contains oestradiol, hormones derived from plant sterols. The older Premarin range of HRTs are made using pregnant mares’ urine and involve terrible cruelty – obviously to be avoided.
More studies are needed to investigate how different foods can help promote sleep but the research looks promising. Foods rich in melatonin, or that help us produce melatonin, could not only combat insomnia but may also provide many other health benefits.
In summary, a varied vegan diet rich in fruit and vegetables, wholegrain foods, pulses, nuts and seeds, coupled with regular exercise and daytime light exposure can help you achieve a good night’s sleep.