Sleep: The Secrets and the Science

We can define sleep as ‘the physical and mental state where we are rested’. Although some people may have historically considered sleep a sign of weakness, it is a pivotal and essential aspect of maintaining mental and physical health.

How much sleep do we need?

We spend over 30% of our life asleep, yet sleep issues such as insomnia occur in up to a third of the population, and many other sleep conditions exist. In adults aged 18-64, the recommendation is to aim for 7-9 hours of quality sleep per night.

How and why do we sleep?

Our body has a 24-hour internal body clock (known as our circadian rhythm). We know this because when we travel and adjust to different time zones, the 24-hour body clock can become shorter or longer, and we can experience this as jet lag.

Many inputs can influence our sleep such as light, food, and fluid (e.g., dehydration can worsen our sleep quality, and too much fluid can lead to frequent urination at night). The output is the quality and nature of our sleep and the benefits associated with good quality sleep.

During sleep, we consolidate and repair, form memories, and adapt our muscles to the exercise we do at the gym. Lack of sleep is not conducive to meeting training goals; just as much as we need to train and exercise, we need to rest, adapt, heal, and repair during sleep.

The sleep cycle

When we sleep, we transition through various stages of sleep. The first stages (1-3) are known as non-rapid eye movement. This is our restorative sleep, which is shown as slow waves if we look at the electrical activity in our brain. After we progress from stage 1 to stage 2 and then to stage 3, we then transition to rapid eye movement, which is the deep dreaming stage of sleep. It is known as rapid eye movement, as our eyeballs move rapidly during this time. We then cycle through these stages multiple times per night, and these stages make up the sleep architecture.

Hormones and sleep

There is a role of hormones before and during sleep, and they wake us up from sleep.

1. Melatonin, the sleep hormone, is secreted when it is dark from an area of the brain called the pineal gland. This gland causes changes in our body, lowering our temperature and initiating sleep.
2. Cortisol is implicated in stimulating the changes necessary to help with the morning awakening response and process.
3. Other hormones and levels are impacted by sleep, too. For example, the hunger hormone ghrelin and the fullness hormone leptin may become imbalanced with lack of sleep, causing issues with hunger and fullness.
4. Testosterone and growth hormone levels also fluctuate during sleep to assist with adaptations. Poor sleep can lower these levels, which can impact sex drive and energy.

What is the impact of lack of sleep on our health?

Lack of sleep can negatively impact on our physical health. Below are some ways in which lack of sleep may manifest itself in our health:

1. Appetite can increase by up to 30%, which can lead to an increased risk of obesity. The reason for this is thought to be that lack of sleep reduces the satiety and fullness hormone leptin.
2. High blood pressure: When we sleep, part of our automatic nervous system, the parasympathetic nervous system, which has a calming effect, is activated. Lack of sleep can cause the sympathetic nervous system, known as the fight-and-flight system, to be heightened, which can be linked to high blood pressure.
3. Poor sugar control: Lack of sleep raises cortisol, the stress hormone, which can cause dysregulation in the way we control our sugar levels.
4. Weakened immune system: Lack of sleep is linked to the lower functioning of the cells that fight infection.
5. Poor mental health: We know mental health conditions such as depression and anxiety can be made worse by lack of sleep, and the presence of these conditions can worsen sleep too, a double-edged sword.

What can we do in our lifestyle to help with sleep?

Nutrition

1. We should avoid eating too much carbohydrates before bed. While this may make us feel sleepy, evidence suggests it can lead to a more disrupted night’s sleep and impact sleep architecture.
2. Avoid caffeine within 6 hours of bedtime. We see so many people drinking 4-6 cups or even more of caffeine a day and struggling with sleep. Reducing caffeine, switching to decaffeinated versions if possible, and minimising the amount of caffeine after midday are sensible options. Camomile and lavender tea can sometimes help people relax before bed, too.

Exercise

1. Don’t exercise too close to bedtime. This will increase adrenaline, dopamine, and energy levels and can impact sleep initiation.
2. Ensure that you get exercise earlier in the day, ideally outside, to expose yourself to sunlight and vitamin D. Note that vitamin D can impact the secretion of melatonin at night, so if you take it as a supplement, it is best taken with a fatty drink or meal in the morning or lunchtime rather than at night.

Toxic substances

1. Alcohol – this is an interesting one. When we are perimenopausal and menopausal, anxiety can be higher in this midlife time (due to low progesterone and low GABA (the calming chemical). This can impact sleep. Also, hot sweats and even going to pass urine often at night in the menopause transition can affect sleep. We see, therefore, many people reach for alcohol to help them sleep in this phase of their lives! And yes, alcohol may help initiate sleep. But what alcohol does is also impact our progression through the various sleep stages, and therefore, the sleep quality we experience can be poor, and we can feel groggy in the morning; one reason for us feeling like we have a hangover is being tired and unrefreshed. So, instead of choosing alcohol to help with your sleep, which conversely does the opposite, try to engage in mindfulness or meditation practices before bed to activate the calming nervous system and help sleep.

Environment

1. Make sure the room is dark enough to stimulate melatonin secretion, which will help initiate sleep. No late-night Instagram scrolling or TV watching in bed! This may be very hard for people to adopt, so perhaps blue light-blocking glasses can help reduce the exposure of this light to the brain. Blackout blinds/curtains and wearing eye masks at night can also be helpful for some people to prevent light inputs from disrupting sleep.
2. Make sure the room is room temperature, not too hot or too cold. Socks in bed and a warm bath can also help initiate sleep.
3. Make sure the bedroom is quiet! No ticking clocks in the background!

As we can see, sleep is complex, and many intricate factors influence its quality.  Many lifestyle measures can be adapted to improve sleep quality, which will, in turn, help with hormonal balance.

For more in-depth reading of sleep and how it can impact our hormones, my book Happy Hormones, Happy You (Beaten Track Publishing 2023) explores this in more detail with case studies looking at how the perimenopause transition and menopause can impact sleep and what we can do. Available to buy from Amazon for £12.99. Dr Milli sees patients privately. To arrange an appointment and free discovery call to better health – visit www.drmilli.co.uk

Dr Milli shares her thoughts on the benefits of positivity and community here.

NorthernLife June/July/Aug 24