Welcome to our latest article from Ludmila, our Primary Care Network Health & Wellbeing Coach.
Please read on. And come back next week for our post on specific things you can do to improve your sleep.
Sleep: so much more than rest
- When we sleep, we lose weight.
- When we sleep, we fight infections.
- When we sleep, we repair structures.
- When we sleep, we rejuvenate.
- When we sleep, we consolidate learning.
Are you getting enough sleep at night to fully function in the daytime? What else could you be missing out on?
How is sleep regulated?
The main hormone associated with sleep is called melatonin. Melatonin production in the brain is stimulated by darkness and suppressed by light. That is the reason behind the advice to avoid light exposure from screens such as phones and computers at night. The threshold to suppress melatonin has been estimated to be as low as 30 lux, which is well below normal fluorescent light of about 300-400 lux. The light picked up by our eyes informs the brain of how much melatonin to produce. Exposure to light at night will therefore suppress our ability to produce melatonin. With suppressed melatonin, we suppress sleep. With suppressed sleep, we may be missing out on a lot more than rest.
What else happens when we sleep?
The sleep hormone melatonin controls a whole load of other functions in the body. As the brain gets off to sleep and skeletal muscles remain still, the body switches to a completely different mode of action that allows for other parts of the system to boost. Some systems increase their activities whilst the brain and the muscles decrease the demand for energy. The brain is incredibly power hungry, and it consumes a lot of the available energy generated in the daytime to maintain cognitive and social activities. At night, during sleep, there is a shift in activity and even weight loss is promoted throughout the night – that is if you get a good night of sleep and respect your circadian rhythms. As we stop eating whilst we sleep, fat cells should come to the rescue and provide much of the energy necessary for running the system overnight. This is especially so when we stop eating early enough in the evening to allow a few hours before we go to bed. Not everyone manages to rely on their fat reserves to make it through the night though and this is one of the reasons why people might sometimes wake up in the middle of the night struggling to fall back asleep. When our fat cells are not flexible enough and we rely on constant food intake for energy, we train our bodies not to rely on stored fat and the result could be a rush of adrenaline late at night. When blood sugar falls below a certain level, adrenaline is released with an alert to the system of low energy to make it through the night. Adrenaline will trigger the release of emergency reserves of sugar stored in the liver but at the cost of stress to the system and inability to relax back into sleep.
Our natural daily rhythm – why is it important?
An energetic switch from brain to immune system also happens at night. During the day, and in health, the immune system works more in surveying mode which is cheaper and allows for the brain to be prioritised with energy during waking hours. At night, or when we fight infections or disease, the immune system behaves differently taking up more energy to increase its functions. The immune system gets on with a lot of housekeeping in preparation for the next day. It not only protects us from invading viruses, bacteria, and other microbes but also promotes repair and rebuilding of structures that get damaged through wear and tear or injury. The switch from day to night, brain to immune function, food to fat is part of what we call circadian rhythm. Our bodies follow hormonal signals that keep this switch regularly aligned with the changes between light and darkness. A regular sleep pattern means we allow the body to attend to many maintenance functions that require night-time hormones and a resting brain for the work to be carried through.
Sleep and disease – how do they connect?
Sometimes the immune system might take over daytime activities and literally put us in bed. A good example of that is when we fall ill with the flu. Chemical reactions happen faster in higher temperatures, so we develop a fever to accelerate these reactions in the fight against infection. As the brain gives way to the immune system to defend the body, we develop what is known as 'sickness behaviour'. We literally become withdrawn and tend to stay in bed. When the fight is over and the inflammation starts to abate, the energetic drain is alleviated, and we regain the interest in social life and engagement with other complex cognitive activities. It is possible to notice how the need for sleep increases if the body is busy defending or repairing parts of the system.
When we disregard our needs for regular sleep, especially over prolonged periods, the whole system is impacted and desynchronised. It is no coincidence that, when health first starts to decrease, sleep problems tend to show up first. Soon, if unaddressed, these problems can progress towards inflammatory states that can lead to diseases, chronic pain and fatigue further down the line. Inflammatory chemicals increase in response to short or disturbed sleep. Ongoing states of low-grade inflammation are linked with increased risk of cardiovascular, neurodegenerative, auto-immune diseases, diabetes and chronic pain conditions.
So making an effort to keep to a regular sleep routine and respecting the time limit for exposure to light may be a worthy habit to maintain. As always, our bodies are highly dynamic and sophisticated systems that interconnect and self-adjust with a precision we are yet to appreciate. It pays to invest in a healthy lifestyle and to consider how or choices today may impact our lives tomorrow.
Come back next week for specific tips on improving your sleep…
By LUDMILA ENTICOTT