Sound sleep: Surprising brain and mind benefits

In the first half of our lives we resist it and in the second it may elude us – yet regardless of our age, sleep is essential for good health across our lifespan. So much so, that our bodies spend almost one third of our lives asleep.

This isn’t an evolutionary accident. Our bodies and brains rely on the gifts of sleep for our mental wellbeing, cognitive function, and physical health.

It may feel like you “switch off” when you sleep but your brain is still extremely active. During the night, your brain cells kick into restoration and regeneration, and your memories and emotions go through important processing. Sleep allows recovery not just physically but also psychologically.

Let’s look at the main reasons why we need sleep:

• Cognition: Sleep supports attention, concentration, working memory and learning ability.

• Emotional health: For example, the amygdala (a brain region involved in our stress response) is more reactive after poor sleep.

• Mental wellbeing: Sleep deprivation is associated with poorer mental health outcomes.

• Protection against disease: Poor sleep increases risk factors for chronic diseases, suppresses the immune system and can even alter blood sugar control.

• Dementia prevention: Good sleep is protective against Alzheimer’s Disease. This is why sleep is a key part of research in the healthy brain ageing lifestyle interventions at the Thompson Institute. 

What happens when we sleep?

During sleep your brain engages in activities that it cannot perform while awake.

Each night, our brain works its way through “cycles” of sleep. Each cycle lasts about 90 minutes, during which we move from lighter to progressively deeper stages of sleep, finishing with a period of dreaming (also known as REM or rapid eye movement sleep). The average adult completes six cycles in a full night of rest.

Throughout these cycles, memories form, emotions get processed, learning consolidates, hormones are regulated, and neurons multiply.

The brain also undergoes what can be likened to a bath – waste products of the brain’s busy daily processes are cleared, particularly during deep sleep.

What is good sleep?

There are three key ingredients to reaping the fullest health benefits of sleep:

• Quantity. This can vary but the average adult needs 7-9 hours per night. Adults older than 65 years may need less – aim for 7-8 hours.

• Quality. While it is normal to wake a few times in the night, your brain needs uninterrupted 90-minute cycles of sleep to function optimally.

• Consistency. It is better to have consistently adequate sleep most nights, rather than under- and over-sleeping on a regular basis.

How sleep is regulated in the brain

You may have heard of the “circadian rhythm”, which is sometimes referred to as the body clock. This rhythm is regulated by internal and external factors.

Internal factors include:

• The suprachiasmatic nucleus: A brain region that acts as a pacemaker for sleep and wake cycles.

• Melatonin: A hormone that is essential for the sensation of “sleep pressure” (i.e. urge to sleep) at night.

• Adenosine: This neurotransmitter builds up in the brain the longer we are awake and makes us feel tired.

External factors include:

• Light: Morning light stimulates the release of cortisol, which is needed to feel alert and energised. Too much artificial light in the evening however can block the production of melatonin, which is needed to feel sleepy.

• Temperature: A drop in core body temperature before bedtime helps to prime the brain for sleep.

Tips and strategies for sleep

• Have regular sleep and wake times to maintain your circadian rhythm. Attempt to have the same routine during the week and weekends.

• At night, limit bright lighting and put your screens away two hours prior to bed.

• In the morning, expose your eyes to bright natural light in the morning to regulate the sleep wake cycle.

• Consider the environment. Ideally, your bedroom will be cool and dark, with limited noise and clutter. Having a comfortable pillow, bedding, and mattress is also important.

• Avoid heavy meals and physical activity close to bedtime. Reconsider your consumption of caffeine after 12pm (note: individuals differ in sensitivity, so discretion is key). Be mindful that drinking alcohol can interrupt your sleep cycles.

• Manage anxiety. Churning thoughts about the future or past impact your ability to fall and stay asleep. Avoid clock watching. Shift your focus to something else, such as gentle music, a mindfulness meditation, or breathing exercises.

Lastly, seek medical advice for underlying medical conditions such as snoring, obstructive sleep apnoea, insomnia, mental health concerns, continence issues, and restless legs.

How can ageing affect sleep?

Some older people find it harder to consistently get quality sleep. This can be due to changes to our body clock, certain medications or health issues. The Sleep Health Foundation offers free resources for better sleep in older age, including:

• Exercising during the day to help build sleep fatigue at night.

• Limiting naps to 15-20 minutes per day.

While it can be tempting to think of sleep as inert, the benefits to our brain and body are far-reaching. Try these tips to get the most out of your time in bed and reach out to a GP if you have any concerns with your sleep.