Sleep is a complex behavioural state. The individual is disengaged and unresponsive, and bodily functions occur at a slower pace (1). The human body runs on circadian rhythm, a 24-hour cycle regulating bodily functions such as sleeping and waking patterns.
Humans spend more than 30% of their life asleep, but the reasoning behind this remains unclear. The purpose of sleep, according to the repair and restoration theory, is physical and mental rest. Sleep is necessary to recover from a wakeful period and to be able to function in a subsequent period of wakefulness (2).
What happens when you do not get enough sleep?
An alarming health concern facing society today is sleep curtailment and the associated impacts on our diets. In the fast-paced society we live in, many find themselves sacrificing sleep in favour of work or study. Prolonged sleep restriction can harm the functionality of various systems in the body (3, 4, 5). Periods of sleep deprivation can cause fluctuations in metabolic functions such as appetite, food intake, glucose tolerance, carbohydrate metabolism, and protein synthesis. The immune system becomes prone to increased inflammation. The endocrine system is at risk of unbalanced hormonal functions. A lack of sleep affects emotional well-being, cognitive function, and physical health. It contributes to poor cardiovascular health, obesity, and increases the chance of developing metabolic disorders such as diabetes (3, 6).
Do you fall victim to elevenses or the 3pm slump? The occasional biscuit with a cup of tea will not do you any harm. If you find you are frequently snacking on high fat or high sugar food items, it may have more to do with your sleeping habits than your willpower. Perhaps you reach home at the end of the working day and order takeaway because you do not have the energy to prepare the nutritious meal you need? The quantity and quality of the foods you choose may be a reflection of your sleeping pattern or lack thereof. Sleep restrictions can increase appetite, create a desire for high-calorie foods, and induce cravings for unhealthy foods (6, 7), resulting in a heightened possibility of over-consuming.
Impact of lockdown on sleeping patterns
We are currently living through unprecedented times, and the full effect that this is having on our sleep health is unknown. At the beginning of the pandemic working from home seemed like a holiday from the real world. The harsh reality has set in, and many of us are now sleeping less and stressing more, what effect is that having on your nutrition?
The external environment plays a pivotal role in aiding the sleep/wake cycle. In the daily occurrence of sunset, the body releases a hormone called melatonin that induces a sense of sleepiness. Exposure to light from computers, smartphones, tablets may disrupt natural production by tricking the brain into thinking it is still light out. The majority of the UK population are now working and learning from home with a considerable increase in screen time. Instead of popping in to meet a colleague at their office, you find yourself in back-to-back virtual meetings. Instead of meeting a friend for a post-work glass of wine, you drink a bottle at home on the couch while watching a movie. The gyms have closed, you cannot travel outside a certain radius, the weather is colder, and you are less physically active. You stress about job safety, finances, cancelled plans, and with each additional lockdown, your stress levels rise. The current global pandemic is a hot topic across numerous social media platforms. Engaging in stressful content close to bedtime may subconsciously stimulate a stress response, evoking fear, anxiety, and other emotions.
How can we improve sleep quality and quantity?
Sleep duration recommendations, according to the National Sleep Foundation (NSF) change throughout the life cycle. Sleep duration is high as an infant to facilitate developmental changes, both mentally and physically. Development needs decline with age, and therefore you require less sleep. The optimum sleep required by a healthy adult ranges from seven to nine hours a night (8). Sleep is essential for survival. But how is it measured and what exactly quantifies good sleep health? Is the level of satisfaction we feel post-sleep dependent on factors such as appropriate timing, adequate duration, and sustained alertness? Can we improve sleep health? According to the World Health Organisation (WHO), health is not merely the absence of disease. In the same manner, sleep health should not be defined exclusively by the mere absence of a sleep disorder.
Often it is assumed that retiring to bed at an early hour may offer a short-term solution to occasional sleep disturbance, but going to bed and falling asleep are two separate entities. How can you ensure the time you spend in bed is beneficial to sleep health? Nutritional management is a possible, convenient, and inexpensive strategy. Different components of the diet components can directly affect sleep. No individual food or drink will make you sleep faster, longer, or better. Try to focus on creating healthy habits and implementing small daily changes.
Improve sleep with simple nutritional tweaks
Whether it is a coffee, tea, or a food item that has been fortified with caffeine (energy drink or sweets) when consumed it can still hamper sleep time and quality, as well as increasing the length of time it takes you to fall asleep. Caffeine increases alertness by stimulating the central nervous system and antagonizing adenosine receptors. Caffeine consumption increases a state of alert and diminishes inclination to sleep (5, 9). These effects may be visible within 15 to 30 minutes of ingestion. The half-life of caffeine, the time it takes for the body to eliminate 50%, ranges from 2 to 8 hours, depending on several factors, for example, age, and health status. Intakes up to 400mg per day (about 5.7mg/kg body weight per day) are deemed safe. Despite its safety, it is not necessarily healthy to consume such quantities regularly (10). As well as reducing your caffeine intake, try putting a time limit on it. Choose a bedtime, and work backward from there using the half-life of caffeine. For example, if you want to be in bed asleep by 10 pm, try drinking caffeine-free beverages after 2pm.
Food containing melatonin, a sleep-inducing hormone, may directly affect sleep. A high fibre diet consisting of vegetables, fruits, and whole grains provides considerable dietary melatonin (5). Aim to eat five portions of fruit and vegetables every day. An increase in circulating melatonin may help with all that extra screen time!
Chrono-nutrition (the timing of eating)
The closure of restaurants during lockdown has led to an increasing number of outlets operating on a delivery basis. Late-night takeaways are more accessible and tempting. Cleverly targeted television adverts work in tandem. Be mindful that digestion slows while you are sleeping. Going to bed on an uncomfortably full stomach is not ideal for sleep health. If you are hungry before bedtime, choose low glycaemic index and complex carbohydrates such as oatmeal or whole-wheat toast that digest well. Limit spicy and acidic foods in the lead up to going to bed, anything that might cause trapped gas, heartburn, or hiccups, and make it difficult to sleep.
It might make you feel relaxed and sleepy initially, but excessive alcohol consumption can disrupt sleep cycles. It is often associated with low sleep quality and duration (11). The side effects of alcohol, aka the hangover, can also influence food choices in period post-consumption. Drink alcohol responsibly, consume moderately, and follow national guidelines (no more than 14 units of alcohol a week). There is a broad range of low-alcohol brands on the market, offering cocktails, wines, and spirits, which offer an alternative to going completely alcohol-free (Unit and Calorie Calculator | Drinkaware).
And remember, be kind to yourself. Stressing about not sleeping will only make it more difficult to sleep!
This article was written by Jen O'Grady and edited by Mei Wan, Registered Dietitian and Nutritionist.
Jen is a final year student reading a Masters of Science in Food, Nutrition and Health at University College Dublin (UCD) and is part of Mei Wan's Nutrition and Health Writer Volunteer Team.
Contact Jen on LinkedIn.
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