We know that getting a good night’s rest is important for our overall health and wellbeing, but are there certain foods or nutrients we can eat that will actually improve our ability to sleep?
Dr Chris Irwin is an Accredited Practising Dietitian, Senior Lecturer in Nutrition and Dietetics at Griffith University and nutrition researcher. He also began his career as a high school physical education and science teacher. He says he’s been interested in the relationship between nutrition and sleep for a long time, and much of his research is centred on this topic.
‘I’m really motivated to help us better understand how we can modify lifestyle behaviours; specifically dietary intake, as a way of contributing to improving the quality of our sleep. I think ultimately sleep is one of the most underappreciated pillars of health,’ he tells Wellbeing by Teacher.
Irwin’s research on nutrition and sleep has involved looking at what can be done to counteract sleep loss, including the use of caffeine. He’s also collaborated with colleagues to explore the influence that diet can have on sleep. Most recently, he’s been working with researchers from Central Queensland University on a narrative review of existing evidence exploring the effects of dietary factors on sleep in older adults.
In recent years, sleep has become an area of health that people are keen to learn more about, and Irwin says he’s often asked which foods might improve a person’s ability to sleep well. While there are some foods that can support a better night’s sleep, Irwin says it is a little more complicated.
‘We need to appreciate that diet is only one component in a very complex model that can influence both the duration and quality of sleep,’ he says. ‘So things like sleep hygiene (i.e. our habits such as bed/wake time and use of technology), the sleep environment, room temperature, noise, and darkness. Someone with medical conditions could also have complications with their sleep. If they’re experiencing pain or anxiety for example, that could influence their sleep.
‘Likewise stress, medication use, all of these things could have an influence on sleep. And there are lifestyle behaviours as well – so things like smoking, physical activity level and diet plays a part of that. We’ve got to get lots of things right to make sure they all have a positive impact on our sleep.’
When considering specific foods or diets, Irwin says there is potential for certain dietary factors to have a positive impact on sleep, particularly foods that are high in tryptophan, an essential amino acid found in protein rich foods like milk and tuna, chicken and turkey, cheese, nuts and seeds, and even chocolate (in small amounts).
‘Tryptophan seems to have an impact on sleep because it gets converted into serotonin which acts as a neurotransmitter in our brain, and then that gets converted into melatonin, a hormone that helps us with the timing of our circadian rhythms (our 24-hour internal clock), or our sleep wake cycles,’ Irwin explains.
‘There’s been some good research showing that specific foods such as cherries and cherry juice can be beneficial to sleep. This is because cherries have high levels of phytochemicals, including things like melatonin and serotonin.’
Unhealthy diets and sleep disorders
In contrast, eating an unhealthy diet is detrimental to many aspects of our overall health, including sleep.
‘Having an unhealthy diet for a prolonged period of time is going to put us at risk of gaining weight and we know there’s an association between obesity and sleep disorders like obstructive sleep apnoea, which essentially causes impaired breathing and often results in an increased number of awakenings during the night time because we’re unable to breathe properly,’ Irwin shares.
‘There are lots of lifestyle factors that are strong determinants of becoming overweight or obese, and having a poor diet is of course one of those. So, it’s so important that we have a good balanced diet that meets our energy needs and doesn’t contribute to excess body weight as a way of reducing the risk of developing associated sleep disorders like obstructive sleep apnoea.’
Which foods negatively affect sleep?
Irwin says there are some really obvious culprits when it comes to specific foods or nutrients that can negatively affect sleep.
‘Caffeine is almost a no-brainer. It’s a stimulant and one of the challenges with caffeine is it actually has a reasonably long half-life. That means it stays in your system for quite a while after consumption, so it’s half-life is about four to six hours, which means that if you consume caffeine, and it could be from any type of source (e.g. coffee, tea, energy drinks, etc.), it’s going to take four to six hours to break down half of that caffeine in your system and then another four to six hours to break down another half,’ he explains. So you want to avoid consuming caffeine well before bed time.
Alcohol can also negatively affect a person’s ability to sleep well. Irwin says that while this may sound counterintuitive with many people reporting that when they drink alcohol they feel sleepy, alcohol does negatively affect the quality of that sleep.
‘The reality is that alcohol can act as a sedative – it can induce feelings of relaxation and sleepiness, making you go to sleep faster, but it has detrimental effects thereafter during our sleep. When we sleep we go through sleep cycles or stages that repeat a number of times throughout the night,’ Irwin explains.
‘We call them non-REM and REM sleep, and alcohol can actually suppress our REM sleep and that basically results in us waking up earlier and waking up more often during the night, so it interrupts our sleep and that can affect our sleep quality and may have detrimental effects the next day.’
Consuming spicy foods before bed may also affect your ability to sleep, although this is more likely to occur in people who suffer from gastro-esophageal reflux.
‘Spicy foods can irritate our digestive tract and cause heartburn, and when laying down it may exacerbate those effects, causing discomfort and then interrupting sleep. It’s not something that will affect everybody, but for people who are prone to experiencing reflux, spicy foods are things to avoid any time before bed,’ Irwin says.
Tips for improving your sleep
As a general rule, Irwin recommends following a balanced diet that is mostly made up of vegetables, fruits and whole foods.
‘If we’re doing that and following that type of dietary practice, we’re likely to get all of the recommended daily intake of vitamins and nutrients we need and that can also help to contribute to healthy weight and probably better sleep as well,’ he says.
If someone is unsure of how to go about improving their diet, Irwin recommends reaching out and getting support from an accredited practising dietitian.
‘They’ll be able to look at your dietary intake and tailor a diet to meet your needs and that would be the first step then at improving the quality of your dietary intake and your overall health and sleep.’
References and further reading
Bartrim, K., McCarthy, B., McCartney, D., Grant, G., Desbrow, B., & Irwin, C. (2020). Three consecutive nights of sleep loss: effects of morning caffeine consumption on subjective sleepiness/alertness, reaction time and simulated driving performance. Transportation research part F: traffic psychology and behaviour, 70, 124-134.
Binks, H., E. Vincent, G., Gupta, C., Irwin, C., & Khalesi, S. (2020). Effects of Diet on Sleep: A Narrative Review. Nutrients, 12(4), 936. MDPI AG. Retrieved from http://dx.doi.org/10.3390/nu12040936
Binks, H., Vincent, G. E., Irwin, C., Heidke, P., Vandelanotte, C., Williams, S. L., & Khalesi, S. (2021). Associations between sleep and lifestyle behaviours among Australian nursing students: A cross-sectional study. Collegian, 28(1), 97-105.
Deloitte Access Economics. (2017). Asleep on the job: Costs of inadequate sleep in Australia. Sleep Health Foundation.
Gupta, C. C., Irwin, C., Vincent, G. E., & Khalesi, S. (2021). The Relationship Between Diet and Sleep in Older Adults: a Narrative Review. Current Nutrition Reports, 1-13.
Irwin, C., Khalesi, S., Desbrow, B., & McCartney, D. (2020). Effects of acute caffeine consumption following sleep loss on cognitive, physical, occupational and driving performance: A systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews, 108, 877-888.
Irwin, C., McCartney, D., Desbrow, B., & Khalesi, S. (2020). Effects of probiotics and paraprobiotics on subjective and objective sleep metrics: a systematic review and meta-analysis. European Journal of Clinical Nutrition, 74(11), 1536-1549.
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