Sleep! The most neglected aspect of good health

Rini Chatterjee
September 28, 2022
min read

Sleep, most of us take it for granted. We either think we do it well or we don’t think about it at all. Some of us fight with it and that fight in itself is exhausting.

It impacts how we feel as soon as our eyes open, how we anticipate the day will go and informs our emotional response to this.  We then either cast a gloomy shadow over the day ahead or we feel equipped and empowered to deal with whatever is thrown at us.  

Sleep influences more things than you could ever begin to imagine. We talk about nutrition and exercise as the foundations of health, but if you don’t sleep well, or you think you sleep well without optimising for good quality sleep – you are missing a trick.  You may workout twice a day and have very little body fat; you may not eat any refined foods and walk 10 miles a day but, if we don’t optimise for good quality sleep then these efforts are only partially effective.  Get your sleep sorted and that’s the foundation for everything else.

Right now sleep is likely to be a problem for many of us. Millions have lost their incomes, feel disillusioned, demoralised, lonely.  Among other important influences, sleep impacts on our cortisol levels.

Cortisol is the hormone that is meant to peak by the afternoon and drop at night. It is the hormone that gets us ready to tackle the day by releasing glucose, the hormone that spikes when we encounter something we should be fearful of and then starts a cascade allowing us to fight the beast or run from it. It has been noted that most world records in sport are beaten when cortisol is at its peak at around 1-2 pm.

However, or many it is chronically elevated and for others; given the current crisis – it lacks the peaks and troughs from which we derive benefit. We become wired and tired - exhausted but unable to find solace in restful sleep.

Cortisol levels that remain moderately high throughout the day bring with it problems. Cortisol is meant to rise and fall. It is meant to equip us with the armour we need to deal with what’s in front of us, but right now; and to be honest in this modern era – it is high all the time, inducing hypervigilance and anxiety. Chronically high cortisol affects everything, from the way we burn our energy, the way we react to adverse situations, the way we choose to eat AND our sleep.

But, trying to manage this is not out of our control.  In these times when we feel autonomy has been removed – it may be helpful to take back some control.

Cortisol isn’t the only factor involved in sleep and this post aims to give you some tangible, easy ways to take back some control.

What is sleep?

There are 5 stages of sleep

Non REM (Non Rapid Eye Movement)

4 stages  

1 and 2 – Light sleep

3 and 4 – Deep sleep

REM  (Rapid Eye Movement) Sleep

Every 90 minutes we cycle through all these stages of sleep

And all stages are important for different aspects of health.

In the first half of the night the majority of our sleep is ‘NREM’ and the latter half ‘REM.’

This is important because if we only sleep well in the latter part of the night we miss out on deep sleep and vice versa.

What is good quality sleep?

The foundations of good sleep are:

  1. Regularity – Your sleep schedule -maintaining the same bed and rise time.
  2. Continuity – Sleeping through and not waking up repeatedly having ‘fragmented sleep’.
  3. Quantity- The total amount of each stage of sleep.
  4. Quality-  the quality of each stage of sleep – impacted by alcohol, caffeine.

Sleeping 6 hrs a night qualifies you as being underslept.

Things that sleep does:

It cleans your brain

Non-REM sleep literally cleans your brain. The glial cells (a type of brain cell) shrink and cerebrospinal fluid fills the space and washes away toxins and any build up of substances like amyloid. Amyloid has been implicated in conditions such as Alzheimer’s dementia but the causes of this are not set in stone.

Less than 7 hrs sleep is thought to  cause issues with this process.

Not sleeping well in the first half of the night does the same.

It protects new learning

If you don’t sleep well before or after trying to learn something new, it doesn’t stick around as well as when you are well slept. Also you have to be well slept to refresh your brain for new learning.

It affects fuel partitioning

‘Respiratory Quotient’ (R/Q) goes up when we are sleep deprived. What does this mean? It means we burn glycogen (sugar stored in our muscles and liver) as opposed to fat. We have limited glycogen stores and endless fat stores….

This literally means that when we don’t sleep well we are crap at burning our fat stores.  In fact, there is some evidence that in people on calorie restricted diets that don’t sleep well – the majority of weight loss comes from burning lean muscle and not fat. NOPE – not good. Muscle is a longevity organ. We don’t want to be consuming our muscles stores and leaving the fat behind.

Sleeping for 4 hrs reduces our insulin sensitivity AND affects the amount of insulin released from the pancreas. (For those who are biochemically inclined, it is thought that twice as much insulin is required for AKT to be phosphorylated for the GLUT4 receptor to move to the cell membrane to allow glucose into the cell, in under-slept people).

We want to go to our graves having secreted the least amount of insulin through our lifetimes as possible. The area under that curve needs to be small. Insulin resistance and metabolic dysfunction have a causative role in many chronic diseases – high blood pressure, heart disease, type 2 diabetes, cognitive decline, polycystic ovarian syndrome, the list is long and affects millions of people and their quality of life. There is increasing evidence to suggest that the comorbidities involving hyperinsulinemia and pathological insulin resistance are more prevalent in the sicker patients with Covid -19.

It affects our chances of having a heart attack

This sounds dramatic but there is evidence that in the States that after daylight savings there is an increase in heart attacks. There is also an increase in car accidents, suicide and Judges passing harder sentences – all potentially related to less sleep. Not much else has changed for the whole population other than time in bed. WTAF. This is of course correlation rather than causation type conclusions, but repeatedly? Maybe sleep has a part to play here.

It affects your fertility hormones

Men that sleep less than 6 hrs a night reportedly have the testosterone levels of men 10 years their senior.

Men who sleep less than 5 hrs have smaller testicles than their counterparts that sleep 7 hrs.

Women who sleep 5-6 hrs a night have a reduction in hormones that facilitate egg production.  potentially one third of women may exhibit menstrual cycle disruption.

It impacts the immune system

Night time shift work has been categorised as carcinogenic by WHO. Now, we might not all agree with what the WHO has to say on some things but there is unlikely to be much agenda for commerce here.

There is evidence that suggests that just one night of poor sleep can reduce the activity of your natural killer cells . If you have your flu jab after a poor night’s sleep it is less effective.  Again – wow, surely the effort to improve sleep is worth it.

It affects our emotional resilience

The prefrontal cortex is involved in logical, rational thought and decision making. It works in conjunction with amygdala, the emotional centre of the brain. Good quality sleep balances these two areas. Chronically poor sleep means that the prefrontal cortex that regulates the emotional amygdala starts  losing at the balance game. We become irritable, poor decision makers, snappy and easily frustrated swinging between positive emotions and major lows.

For you athletes

The last bit of sleep before we wake to face the day is important in muscle memory development, the embedding of the fine motor skills. The millisecond/millimetre between gold and silver. Research also shows that chronically underslept athletes are more prone to sports injury risk.

So, what can we do to optimise sleep?

It may take time to fall into a better pattern but, is there anything we are in control of to ensure that we are doing all we can to prevent adverse effects from lack of sleep?  

Yes, there are simple things that are within our grasp.

The hormones involved in sleep

Hickie, Ian & Naismith, Sharon & Robillard, Rébecca & Scott, Elizabeth & Hermens, Daniel. (2013). Manipulating the sleep-wake cycle and circadian rhythms to improve clinical management of major depression. BMC medicine. 11. 79. 10.1186/1741-7015-11-79.

How can we influence this cycle?

Firstly – allow yourself the opportunity to get 8 hrs sleep. That means don’t get into bed at midnight and expect to get a solid 8 hrs in by 8am. You need some buffer time.


Cortisol is the hardest chemical to influence. The evidence points towards mindfulness and meditation here.  This feels so far outside of our capabilities as humans in 2020 it’s unbelievable.

1. Breathing techniques can also be infinitely helpful. See the previous post on isolation and regathering for some breathwork protocols.

2. Your emails, messages and incessant checking of twitter will influence cortisol levels. Try to distance yourself from your phone for a couple of hours before bed.

3. Getting sunlight within 30 minutes of waking or, the use of an all spectrum light box in the morning may help regulate the diurnal rhythm of cortisol.

4. Mindfulness meditation - help identify and shut off the chatter.

Some accessible ways to access the benefits.

Apps like:

10% happier

Waking up




Google ‘blue light filter for your phone’ and set an easy click pattern to turn it on.


Melatonin should be low in the day, rise in the evening to a peak at night and then drop off. It makes us feel sleepy. For optimal levels of melatonin we must acknowledge the influence of light and our gut health.

Melatonin rise is delayed by blue light. Blue light is pervasive, we live in a world without normal light rhythm. The advent of electricity means it can be (and generally is) ‘light’ all the time.

IPads, tablets, the TV, our phones all emit blue light that can delay the peak of melatonin by up to 3 hours – which is why you may feel tired and go to bed and just not manage to get off to sleep.

– Dim the lights – use lamps in the evening.

– Put phones down. Turn off tablets and tv’s within 2 hours of sleep, or try using blue light filters on your phone, apps like F.Lux on your computer, or blue blocker glasses.

Melatonin is also made from serotonin which affected by oestrogen levels and your gut. Consider giving refined grains , refined sugars and refined oils the swerve – there's a common denominator here. Eat whole foods  meat, fish, eggs, vegetables, dairy - they are delicious and nutrient dense!


Think of this as your bank account. You save it up and when you spend on your account, the balance drops. With adenosine you save it through the day. The savings build to that delicious feeling of sleepiness when you just can’t keep your eyes open!

Naps in the day and caffeine both affect how adenosine does its job and both of these things mean you’ve spent cash. Then you have to start saving again.

Only people with regular, healthy sleep should nap.  On days when you’ve been caught short, when you’ve optimised for good sleep, a nap can be invigorating and required. More importantly it is unlikely to affect your regular sleep patterns. If you’ve got a poor sleep pattern and regularly nap because you’re too exhausted for life – you’re using up your adenosine in the day and the night time ‘sleep pressure’ just won’t come. Round and round, you’ll go into the cycle of poor sleep.

Adenosine binds to a receptor in the brain to make you feel sleepy. Caffeine also binds to this receptor and stops the adenosine binding – therefore inhibiting that pressure of sleep.

Caffeine has a half-life of approximately 5-8 hours. That means 8 hrs after drinking a cup of coffee or [insert favourite caffeinated drink],  half the amount of caffeine is still affecting you 8 hrs later. So, figure out when you want to be asleep and determine when your last cup of caffeine should be. The sensitivity you have to caffeine may differ from the next persons, but unless you are monitoring your sleep, it's probably better to limit caffeine later in the day.

For example, you want to go to sleep by 10, get into bed by 9, any coffee you drink at 2pm will still be milling around. I know – gutted…

I’m an early bird. I naturally feel sleepy early in the night, get to bed early to try and to be asleep for approx 2100hrs. I also rise early – approx 0545hrs. This is genetically determined – you are either a night person or a morning person and given that – my last caffeinated drink is about 10am. Unfortunately work places have not cottoned on to the fact that if they allowed for flexible working times that allowed for this genetic predisposition, they might achieve better productivity from their workforce. This means lots of night owls have been forced into becoming morning larks but they are less than chirpy about it.

Other things that impact a good night’s sleep

Body temperature

Your body temperature needs to drop to induce sleep. With central heating, late eating, exercise within a couple of hours of bedtime and duvets, we can’t be bothered to switch between summer and winter – this can take some doing.  

Have a bedroom temp of about 18- 19 degrees celsius.

  • Try not to eat within two hours of bed.
  • Try not to exercise within two hours of bed.
  • A really hot shower can lower your body temperature by shunting heat to your skin and away from your core.
  • A cold core can mean cold feet which can keep you awake, shove some socks on.

And lastly, booze in the evening…

It wrecks your sleep. It really does. My Oura ring (a tool to monitor things if you so wish) shows (on repeated occasions) an increase in body temperature, respiratory rate, a decrease in my Heart Rate Variability and a huge hit on REM sleep all after just a couple of drinks in the evening. We’re not saying don’t ever drink, but be aware of the effects it has on your sleep.

Sleeping tablets cock everything up. They increase risk of death, cause rebound insomnia, increase the risk of dementia and are usually addictive. Again short term use for things like jet lag may be beneficial, but if you’re using a sleeping aid regularly its causing you harm.

Sleep is essential. Maximise your potential in life by optimising for it.

Resources for you

‘Why we sleep’ Dr Matthew Walker

Rini Chatterjee
Founder, Resilience Health