Are you in need of some good zzz’s? This month, settle into some soothing words from Dietitian Clare as we take a deep dive into…bedtime.
This month I will be exploring the relationship between nutrition and sleep. The quality and length of our sleep can affect everything from cardiovascular health to how we make memories, even our appetites. We spend about a third of our lives sleeping (over 25 years!), so I’ll show you how the right food can help us fall asleep, and get the quality sleep our bodies deserve.
When we leave waking consciousness to sleep, our brain remains active although there are changes in brain wave activity that vary depending on the different stages of sleep we are in. Our heart rate, blood pressure, breathing rate and our body temperature changes, too. Many physiological activities are reduced while we sleep, for example, the production of urine is decreased as our kidney function slows down.
1. Types of Sleep
Sleep is subdivided into 2 main types, NREM (non rapid eye movement) and REM (Rapid Eye movement). These different stages are based on electrical brain wave activity, the higher the number, the deeper the sleep – and the more difficult it is to wake a person up.
A form of NREM sleep that lasts about 1-5 minutes. This is the dozing off period when you haven’t entered deep sleep. The body hasn’t fully relaxed at this point, although some physiological processes and brain activity will start to slow.
Another form of NREM sleep that lasts between 10-60 minutes. At this stage, body temperature drops, breathing and heart rate slows and our muscles relax. Eye movements stop, and electrical brain waves slow with occasional bursts of activity called sleep spindles.
Stages 3 and 4
This form of NREM sleep lasts between 20-40 minutes. This stage is a form of deep sleep, where muscle tone, breathing and pulse rate decrease. There is no eye movement. Brain activity during this stage has a distinctive pattern known as Delta waves. Scientists believe this stage is critical for restoration within the body, with evidence suggesting it may be important for the healthy function of our immune and cardiovascular system. There is further evidence that this stage might contribute to consolidating our memories.
The final stage of the sleep cycle is REM sleep, which lasts between 10-60 minutes. REM sleep is the state in which we experience the most vivid dreams. Electrical brain wave activity starts to speed up again, our eyes jerk rapidly in different directions and our breathing becomes more rapid and irregular. This stage of sleep is believed to be really important for our cognitive functions including learning, creativity and problem solving.
2. What are the benefits of a good night’s sleep?
- Cell repair and growth
- Reproductive and hormone health
- Cardiovascular health
- Immune system function
- Brain health and cognitive abilities
- DNA and gene function
- Mental health
- Gut health and microbiota
- Weight and appetite control
- Blood glucose levels
3. How does what we eat and drink affect our sleep quantity and quality?
The World Health Organisation recommends 8 hours sleep a night, but what we eat and drink can have massive implications for our ability to fall asleep and the quality of sleep we can achieve. The good news is, a few small dietary changes can bring about huge improvements and enable you to have a restful slumber.
The ups and downs of caffeine
What is caffeine?
Caffeine is a psychoactive stimulant found in a number of foods and beverages. Scientists have found that caffeine also prevents deep sleep, so even if you feel unaffected by it, even one standard coffee in the evening will reduce deep sleep by around 20%.
What does it do?
Caffeine blocks adenosine receptors and increases adrenaline production. Adenosine is the hormone that makes us feel sleepy. This temporary block stops us feeling tired.
Caffeine is found in:
- Tea (including green tea)
- Energy drinks
- Soft drinks
- Herbal infusions (such as yerba mate)
- Some herbal remedies and medications also may contain caffeine
- Limit your intake to 1-2 caffeinated drinks per day
- Avoid caffeinated drinks & food in the afternoon
- Be mindful that ‘decaffeinated’ still contains caffeine
- Cut down gradually over a number of weeks
4. Eating for a good night’s sleep
Aim to have regular meals that are balanced between slow-release wholegrain carbohydrates, fibre, a wide variety of vegetables and fruit, lean proteins and poly and monounsaturated fats for sustained energy release. Eating in this way has been shown to aid a good night’s sleep.
Eat foods containing tryptophan
Tryptophan is an amino acid that promotes sleep and is found in small amounts in all protein foods. The best sources are eggs, soybeans, poultry, meat, fish and cheese.
Watch your vitamins and minerals
Ensure your diet includes sources of key micronutrients that are important for sleep, including iron, vitamin D, vitamin C and magnesium.
Drink chamomile tea, try lavender-infused milk, or a bitter orange infusion.
What to avoid:
Ideally your body does not want to be actively digesting food whilst you try to get to sleep so avoid bedtime snacks and avoid fatty foods which take much longer to digest, allow 2-3 hours after eating before going to sleep.
Fluctuating blood sugar levels may also disrupt sleep patterns. Consumption of sugary foods, beverages and refined carbohydrates has also been shown to potentially interfere with tryptophan absorption. This has implications for the production of melatonin and serotonin, hormones that help induce sleep.
5. Top tips for a better night’s sleep.
- Have a consistent, regular bedtime routine to wind down and prepare for bed. This programmes the brain and internal body clock to get used to a set routine.
- Take part in regular physical activity. Regular moderate to vigorous exercise (not just before bed) has been shown to improve sleep for many people.
- Relax! Have a warm bath (not hot), meditate, stretch with some gentle yoga, read a book, listen to the radio, you can even write a “to do” list to clear your mind.
- Make your bedroom sleep-friendly. Fit some thick curtains if you don’t have any. If you’re disturbed by noise, consider investing in double glazing or just use earplugs.
- Keep your bedroom temperature cool. 18C is optimal.
- Avoid laptops, phones and screens for at least an hour before bed.
Still not sleepy?
Don’t stay in bed. Get up and go to a different room and do something different as your brain will associate the bedroom as a place of wakefulness rather than a place of sleep.
Remember, if you are struggling with longer term sleep issues, always seek medical advice from a sleep specialist.
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