The Beauty of Sleep
How did you sleep last night? I sincerely hope the answer is “well”!
I’m sure this is a question you’ve frequently been asked or ask other people… We seem to be obsessed by this simple question and it turns out, with good reason. However, as someone for whom a good nights sleep was elusive for many years, I know only too well that there is nothing worse than being asked, “How did you sleep?” when you’ve barely managed to get 4 hours.
You might be confused as to why, especially in recent years, such a big deal is being made about sleep. We all sleep, albeit some of us more than others. It is a curious evolutionary trait which renders ‘the sleeper’ vulnerable to attack and predation whilst in a state of perceived unconscious paralysis.
So what I want to address today is what sleep entails, why it is so important, as well as some of the more significant health consequences of poor sleep, plus a few tips for how to improve and support sleep quality and quantity.
The Stages of Sleep
As we sleep, we transition through various phases from light non-REM (NREM) sleep to deeper NREM (AKA slow wave) sleep, and into REM sleep. (Please refer to the cover diagram).
REM stands for Rapid Eye Movement, which is associated with the period of sleep when we dream, during this time we are effectively paralysed (having lost all muscle tone) to prevent us from acting out our dreams.
Deep NREM sleep (AKA slow wave sleep), where our brain exhibits the lowest amount of brain wave activity, is considered to be restorative. It has often been considered which is more important and numerous studies have agreed that whilst both play different roles, they are both essential.
Generally speaking, we sleep in 90-minute cycles of lighter NREM into deep NREM and then REM sleep. However, not in perfect proportions. Typically, the early part of night has a higher proportion in NREM sleep and the latter half a higher proportion of REM. A balance of both is vital for health, particularly memory consolidation.
This is overly simplistic as various factors are at play, but research indicates that NREM sleep is more involved in transference of short term to long term memory, as well as clearing out of unnecessary connections that have taken place during the day. REM sleep on the other hand, is involved in fine tuning connections, supporting ‘synaptic plasticity’ (ie. change that occurs at synapses - the junctions between neurons that allow them to communicate) and accelerating connectivity. However, one cannot work effectively without the other.
Interestingly, our ratio of NREM and REM sleep alters throughout the stages of our lives…
Unborn babies spend up to 12 hours a day in REM sleep, as it is vital for promoting brain maturation, developing neural pathways and encouraging synaptogenesis (formation of synapses between neurons). By 6 months, the ratio is 50:50 of NREM:REM. At 5 years old, there’s a 70:30 ratio of NREM:REM and by adolescence NREM sleep is dominant with a ratio of 80:20. In adulthood, our NREM begins to decline and REM sleep begins to increase again. In later stages of life, sleep efficiency reduces further with NREM being worst affected, resulting in REM sleep dominance.
What is ‘Sleep Efficiency’?
Sleep efficiency refers to the percentage of time a person sleeps, in relation to the amount of time spent in bed. Normal sleep efficiency is considered to be 80% or greater and the percentage is the ratio of the total sleep time in a night compared to the total amount of time spent in bed.
E.g. if someone spends 8 hours in bed, but only actually sleeps for 4 of those hours, their sleep efficiency would be 50% (ie. 4 divided by 8 multiplied by 100)
An efficient sleep leads to a deeper sleep of higher quality with fewer interruptions. It usually results in boosted energy levels and feeling well-rested upon waking, while an inefficient sleep may lead to feelings of tiredness and restlessness. For this reason, in order to improve sleep efficiency, aim not to stay on bed for prolonged periods if you aren’t sleeping.
The apparent reduction in sleep efficiency as we age is, at least in part, linked to many health conditions that are associated with advancing age.
Health Conditions Associated with Poor Sleep
a) Cancer
Poor sleep stimulates the sympathetic nervous system, provoking sustained inflammatory response. This sustained inflammation is a driver of cancer due to the initiation of angiogenesis, creating damage and mutations to DNA and helping to trigger metastasis. Therefore, poor sleep can have a profound impact on cancer progression. In vitro studies have shown that sleep deprived mice have a 200% increase in the speed and size of cancer growth. (PMID: 24448240)
b) Alzheimer’s Disease (AD)
It may seem quite obvious that sleep plays an essential role in protecting our cognitive health, however, how sleep protects our brains is not fully understood. Possible mechanisms underlying the reciprocal relationship between the sleep–wake cycle and AD pathology and behaviour include:
Decreased neuronal activity during slow-wave sleep whereby neurons get a “rest” allowing them to repair and recuperate
Deficits in resting state functional connectivity, i.e. during rest new connections between neurons are formed
Clearance of soluble amyloid-beta and toxic proteins during sleep
Reduction of pro-inflammatory cytokines
“Efficient and effective sleep is more than just a luxury; it is critical for the proper function of many organ systems, particularly the brain.” (Musiek et al, 2015)
c) Heart Disease
Sleep has a direct effect on our cardiovascular system and when sleeplessness persists, it can be a driving force of cardiovascular disease, not least due to over activation of the sympathetic nervous system (ie. our stress response). Poor sleep impacts the cardiovascular system by:
Accelerating heart rate
Increasing blood pressure
Eroding blood vessel endothelium
Sleeping only 5-6 hours per night equates to 200-300% greater likelihood of suffering calcification of coronary arteries
People over the age of 45 who sleep 6 hours or less are at a dramatic 200% increased risk of heart attack
d) Obesity
Poor sleep can be a trigger of obesity which has association with multiple health conditions. Again, this process is multi-factorial but even one night of poor sleep increases our hunger hormone, ghrelin, and reduces our satiety hormone, leptin, thereby encouraging an increase in food intake and preventing normal balance of energy intake and expenditure, thus presenting challenges for healthy weight management. (PMID: 27467177)
e) Immunity
Sleep loss alters immune function and vice versa. Alarmingly, short sleep duration of around 4 hours (versus a more optimal 7/8 hours) results in a 70% reduction of natural killer cell activity. What’s more, recent studies have even shown that short periods of sleep loss at the time of having a vaccination can reduce the vaccine’s effectiveness. (PMID: 30867162)
So clearly sleep plays a major role in our overall health. In fact it has an impact on every organ system within the body. Therefore, prioritising sleep is vital for maintaining wellness, throughout life and particularly into old age.
“Short sleep predicts all cause mortality” Professor Matthew Walker, ‘Why We Sleep’ (2017)
On the brighter side, thankfully when we do sleep well, there are many associated benefits…
Sleep Benefits
Better productivity - Extensive research links adequate sleep to better concentration, productivity & cognition
Better weight management - Many studies link obesity and poor sleep patterns, yet other factors (alcohol intake, physical activity levels, long working hours and chronic health conditions etc) may be at play. Poor sleep also likely affects a person’s desire to adopt healthful behaviours
Better calorie regulation - Evidence suggests sleep patterns affect the hormones responsible for appetite. Plus, tiredness naturally leads to a tendency to consume extra calories in a bid to generate energy
Boosted athletic performance - Adequate sleep for adults is between 7-9 hours whilst athletes may benefit from as many as 10. A key reason for this is that the body heals during sleep, potentially resulting in better performance intensity, speed and better coordination, as well as mental function
Lower risk of heart disease - Quality sleep allows blood pressure to self-regulate and in turn reduce the chances of sleep-related conditions (e.g. apnea) thus promoting better overall heart health
Improved social & emotional intelligence - It’s been proven that those who do not get sufficient sleep are more likely to struggle with recognising other‘s emotions and expressions
Preventing depression - Even minimal sleep deprivation over time can affect mood. Reduced enthusiasm, irritability, or even some symptoms of clinical depression, like feeling empty, are common
Stronger immune system - Sleep helps the body repair and recover and may also help us fight infection
There are of course, multiple interventions that can help support healthy sleep, and yet as with most health-related interventions,, there’s no one size fits all solution as it is dependent on various factors.
Tips to Improve & Support Sleep
Establish regularity - Consistently go to bed and wake at the same time each day, 7 days a week
Relax!!! Activities such as yoga, meditation, mindfulness, breathing, reading a book and massage are all helpful. Perhaps consider using a relaxation or meditation app which may help with falling asleep and will certainly aid relaxation
Take a warm/hot bath (ideally with Epsom salts or lavender essential oil) - Hot baths bring blood vessels to the surface allowing your core body temperature to cool which helps the body prepare for sleep as body temperature begins to drop during night. It’s also great for deactivating the stress response!
Ensure daily daylight exposure - To regulate your natural circadian rhythm, whilst topping up serotonin and vitamin D levels
Get (and stay) active during the day - Also avoid exercising late in the evening as this can delay sleep onset
Keep noises down - For me, earplugs are a must for falling asleep and they also help to prevent unnecessary awakenings in the night
Keep the bedroom cool - Most people sleep best at around 18oC with good ventilation
Make sure your bed is comfortable - Waking often with a sore back or neck suggests your mattress and / or pillow may need changing
Turn all lights and screens off - Especially flashing, blinking or bright lights. Mobile phones should not be used in or looked at at least an hour before bed, as the blue light emitted from the screen can stimulate the brain and keep it awake. The best option is to leave the phone to charge in another room (e.g. the kitchen)
Keep a simple gratitude journal - Writing a few things dow which have happened or crossed your mind during the day can been very beneficial in switching off racing or persistent thoughts in your mind
Cut down on caffeine - Ideally no caffeine after midday. Whilst we are all different, some people take up to 12 hours to metabolise caffeine and even if you think you sleep well after a cup of coffee late in the evening, it’s unknowingly ruining the quality of your sleep
Say no to the nightcap - Boring I know, but sadly alcohol is a sedative. Whilst you may think you’re sleeping well as a result of a drink or two pre-bed, sedation and sleep are not the same thing
Observe ‘stimulus control’ - If you are awake for longer than 20 minutes, it is recommended that you get up, leave the bedroom, and do something relaxing. Once you begin to feel sleepy again, return to the bedroom to sleep. This helps to retrain the bed-sleep association in our brain
Finally, before I sign off, I want to share two links with you to videos which I found incredibly eye-opening. Both are by the international guru of sleep and author of the best-selling book, ‘Why We Sleep’, Professor Matthew Walker:
The first is one of the most listened to TED talks ever, entitled ’Sleep is Your Superpower’. You know it’s going to be seriously interesting with an opening line like, “I would like to start with testicles”! Professor Walker beautifully articulates in 19 minutes exactly why sleep is the elixir of life.
The second, ‘How to Improve Your Sleep’, explains in a mere 8 minutes why, amongst other things, alcohol and caffeine are damaging to our sleep and also why, sadly, we can’t bank ZZZs or catch up on lost sleep.
So that’s it! I hope it’s been helpful. As ever, if you have any questions or you want to get in touch and find out more about the coaching I offer please don’t hesitate, I’d love to hear from you - I’m just a click away!
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