We all know the importance of a healthy diet, but sleep is also an important contributing factor towards overall good health. 1 in 3 people suffer from poor sleep, with factors such as stress and technology often identified as the cause of sleepless nights. However, research has shown that poor nutrition may also affect the quality and amount of sleep that we get. Regular lack of sleep can increase the risk of medical conditions like obesity, coronary heart disease and diabetes, as well as shortening overall life expectancy, but how can we use nutrition to combat this? 
Caffeine and sleep
Firstly, lets talk about caffeine. Caffeine is a natural stimulant that increases the activity of your brain and nervous system. It is most commonly found in tea, coffee, fizzy drinks and cacao. Caffeine keeps us awake in a number of ways, such as by blocking adenosine receptors in the brain and by interfering with circadian melatonin rhythms. Adenosine is a chemical that promotes sleep, and it builds up in the brain the longer that we’re awake. When caffeine interferes with the adenosine receptors in the brain, we feel more alert, rather than becoming sleepier. Circadian rhythms are patterns that our bodies follow throughout the day, keeping us awake during the day and more tired at night. When we consume caffeine, these patterns are disrupted meaning that the onset of sleep can be delayed if it is consumed too close to bedtime. Additionally, caffeine has been found to affect sleep quality. When consumed it notably reduces the amount of slow-wave sleep that we get, the stage of sleep that helps us to feel refreshed in the morning.
The length of time that caffeine lasts in the body is usually measured by its half-life. The half-life is the amount of time it takes for your body to process half of the caffeine that you have consumed. Studies have shown that the half-life of caffeine ranges from 4-6 hours. Due to this, it is recommended that you should not have any caffeine less than 6 hours before your bedtime . The NHS suggests that caffeine can be consumed as part of a healthy diet and health organisations around the world suggest that most people can safely consume up to 300mg of caffeine a day . However, it is recommended that pregnant women consume no more than 200mg of caffeine per day . For reference, an 8 ounce cup of coffee contains between 95-200mg of caffeine and a cup of tea contains between 14 and 60mg of caffeine.
How can late night eating impact our sleep?
Eating too close to bedtime is another factor affecting sleep. When we eat too late at night, our digestion muscles have to work to digest the food when they should be resting. This can prevent us from getting the deep, good quality sleep that we need and can increase the time it takes for us to get to sleep. Lying down straight after eating can also be a cause of heartburn, which could cause discomfort and further sleep disruption. To combat this, you should try to stop eating two hours before bedtime and stop eating 3 to 4 hours before bedtime if you experience heartburn. It may also be beneficial to make sure you are having regular meals throughout the day and snacks if you need them as this will prevent you from becoming hungry later on at night . If you do still find that you’re hungry before bed a small snack might not be such a bad idea, but spicy and caffeinated foods should be avoided.
What to Eat for Good Sleep?
A balanced and varied diet is recommended to promote good sleep  and there have been studies that show that “short” sleepers (less than 7 hours per night) tend to have less varied diets than “normal” sleepers (between 7 and 8 hours per night). Additionally, a significant trend has been reported between worse sleep quality and increasing carbohydrate intake, particularly with frequent consumption of energy drinks and fizzy drinks . High carbohydrate intake can increase the amount of times you wake up during the night and decrease the amount of deep sleep that you get. A reason for this could be that meals that cause high blood sugar levels which can lead to poorer sleep, this is most commonly seen in people who suffer from type 2 diabetes or are in the pre-diabetes range .
Top Tips for Improving Sleep
- Try to stop consuming caffeine at least 6 hours before bedtime
- Try to stop eating two hours before bedtime
- Eat regular meals to prevent yourself feeling hungry late at night
- If you do want a small snack before bed, avoid spicy foods and caffeine
- Eat a varied diet, low in sugary carbohydrates
Caroline Hill is a specialist menopause dietitian supporting women making dietary change. Caroline uses her extensive knowledge, skills and expertise of food and nutrition to help women manage their symptoms and weight during menopause. Caroline believes in providing sustainable, individualised, evidence-based advice to women making dietary change.