we’re often being advised — whether it’s by health professionals or the media — to get more sleep.

The internet is swimming with tips on how to improve our sleep hygiene and quality, but why exactly is sleep so important?

Renowned neuroscientist and author of The Neuroscience of Excellent Sleep Dr. Stan Rodski is a respected authority in brain management and performance. His research into the quality of sleep, in tandem with the quanitity, underpins the fundamentals of sleep and how they affect brain function, influence sleep disorders, and prove beneficial to our overall physical and mental wellbeing.

Research led by scientists and experts conducted over the last few decades has given us important insights into the key benefits of sleep. And, since better sleep is one of the most commonly reported effects of hot springs bathing, we thought we’d explore the effects of a good night’s sleep.

the anatomy of sleep

“Sleep is a fundamental aspect of human biology and an essential component of overall health and well being" - Dr. Stan Rodski

Sleep is controlled by two automatic systems: our circadian system and our homeostatic system. The circadian system is our internal body clock — the system that triggers us (via the release of melatonin) to feel sleepier as the sky darkens outside, and to feel more alert as the morning sun beams in through our bedroom window.

The homeostatic system — which is responsible for maintaining homeostasis — tallies the amount of sleep we need in order to balance our periods of activity. It also regulates the number of hours of sleep we need according to our sleep debt, which accumulates during waking hours and it alleviated during sleep.

The functionality of several brain regions also play a huge role in sleep regulation. The thalamus, an egg shaped structure in the centre of the brain, plays a key role in sleep quality, consciousness, cognitive learning and thinking. The prefrontal cortex is also integral in sleep regulation and mediation due to its role in decision making, thoughts, actions, and emotions. This means, when we haven't had enough sleep, it is likely we will feel foggy, and our decision making and judgement may feel a little clouded.

sleep stages

We journey through various phases of sleep throughout the night, and we generally shift between stages every 90 minutes — including REM (rapid eye movement) sleep and NREM (non-rapid eye movement) sleep. REM sleep, which was only discovered in 1953 by sleep research pioneers Aserinsky and Kleitman, is so-called because of the way our eyes move rapidly behind our eyelids when we’re in this sleep phase.

There are four stages of NREM, which are all characterised by slow, synchronised brain waves. Scientists have discovered that NREM sleep is particularly important for helping us regenerate both physically and mentally. This is the stage we usually experience for the first half of the night, and it provides rich, deep, restorative sleep.

REM sleep, on the other hand, is a time of heightened emotional and cognitive activity — including dreaming. Research has found that REM is important for helping us regulate our emotions and store memories. REM sleep is also one of the only times that the stress molecule noradrenaline is deactivated. We usually spend the second half of the night in REM sleep, which tends to be a little more fragmented.

Experiencing a full night’s sleep means we experience the full range of sleep stages and their respective benefits.

benefits of sleep

Improves cognitive function

This is one can be clearly observed: we know that our brains work better when we’ve had a decent sleep. The science backs this up. Quality sleep helps us focus, deal with stressors and operate our executive function, which is responsible for our judgement and perception of events. We make better decisions when we’ve slept well.

Helps with emotional regulation

A solid sleep schedule leads to emotional robustness. When we haven’t slept well, we’re more likely to be reactive, moody, negatively influenced by external stimuli and emotionally dysregulated. Research has also found that sleep deprivation leads to a reduction in empathy.In other words, we’re not our best selves when we’re lacking in sleep.

Boosts immune function

There’s a reason why your doctor tells you to get some rest when you’re unwell: the connection between sleep and the immune system is well documented. A recent study that infected subjects with a live rhinovirus (the virus that causes the common cold) found that those who slept six or fewer hours a night were more likely to develop a cold after being infected than those who slept seven hours or more. One of the reasons is that the body produces infection-fighting cytokines during sleep.

Encourages tissue repair and growth

We might think of the gym as the main place where we strengthen and condition our bodies, but research suggests sleep is extremely important for muscle growth, protein synthesis, tissue repair and growth hormone. These functions occur mostly (if not solely) during sleep.

Balances hormones and removes mental by-products

Scientists have discovered in recent years that sleep plays an essential role in the glymphatic system and removing waste from the brain. It helps clear away substances such as beta-amyloid, a protein whose build up has been associated with the development of diseases such as Alzheimer’s.

Sleep also helps us clear adenosine from our brains — a by-product of mental activity that seems to make us sleepy — so we wake in the morning feeling alert again. Sleep also plays a role in regulating and metabolising hormones such as melatonin and cortisol.

Helps with memory consolidation

Sleep is thought to help us with memory consolidation — the process where a memory becomes stable. Researchers think different brain waves during different cycles of sleep help create different kinds of memory. REM sleep, for example, is important for consolidating emotional, complex and procedural memories, while slow-wave sleep helps consolidate long-term memories.

Improves heart health

When we fall into deep sleep, our heart rate slows — but our heart doesn’t get this natural break if we don’t sleep well enough or for long enough. Proper sleep mitigates our risk of heart disease, heart attack and hypertension.

Helps maintain healthy weight

As well as dysregulating our hormones, insufficient sleep can lead us to feel hungry thanks to an increase in the appetite stimulant ghrelin (which is replaced by suppressor leptin during sleep).It also reduces the risk of Type 2 diabetes by regulating insulin levels.

You can find out more about the connection between geothermal bathing and better sleep quality here, or read about blue light and how to improve your sleep here.