I recently read the book ‘Why we Sleep’ by Mathew Walker and though I knew about the importance of sleep, this book was a real eyeopener. And if you are serious about your health, fitness and wellbeing, then sleep should be your number one focus ahead of anything else you do. It has an absolutely fundamental role on your overall health, weight, exercise, recovery, illness, etc — it literally touches everything you do.
Are you getting enough sleep?
Well the answer is fairly straightforward…. If when you wake up, you could fall back asleep? Then probably ‘no’ and ‘If you can function optimally without caffeine?’ then probably ‘Yes’
If you don’t get enough sleep — your adenosine levels (a hormone that builds up in your brain, creating ‘sleep pressure’) remain high. And that sleep pressure acts like an outstanding debt, the adenosine levels roll over to the next day and the next day etc. which ultimately can lead to chronic sleep deprivation. You can artificially mute the adenosine created sleep signal through caffeine (The levels of circulating caffeine peak approximately 30 mins after oral administration), but the problematic part is caffeine has an average half-life (50% is gone) of 5–7 hours, which means that if you drink caffeine in the afternoon, there is no way the effects will be worn off when you go to bed. (Note: even decaffeinated stuff has still 15–30% of the caffeine in there).
So what are the different stages of a night’s sleep and what happens during these different stages?
Stages 1 & 2: Light Sleep
Light sleep initiates your sleep cycle and acts as a transition to deeper sleep stages. During this stage your muscles begin to relax, your heart rate and breathing slow down, and you wake up easily.
During light sleep, you can expect the following:
muscles relax and may jerk
- respiration slows
- heart rate decreases
- body temperature drops
- sleep begins
Stages 3 & 4: Deep Sleep
Deep sleep focuses on your body. It is the most rejuvenating and restorative sleep stage, promoting muscle growth and repair as well as waste removal in your brain. In this stage, you have difficulty waking up and are disoriented or groggy if awoken.
During deep sleep, you can expect the following:
- blood pressure drops
- blood flow increases to muscles
- repair hormones (i.e. growth hormone) are released
- tissue growth and cell repair occurs
- long, slow brain waves
- brain flushes out waste
Stage R: REM (Rapid Eye Movement) Sleep
REM sleep is essential to re-energizing your mind. REM is associated with dreaming, memory consolidation, learning, and problem solving. The time spent in this sleep stage usually decreases with age.
During REM sleep, you can expect the following:
- respiration increases
- heart rate increases
- temperature regulation is switched off
- brain activity is high; vivid dreams may occur
- body becomes immobile to stop you from acting out dreams
- blood flow increases to genitals
A Full Night’s Sleep
Your body cycles through these stages four to five times each night. Cycles earlier in the night tend to have more NREM (Non Rapid Eye Movement) sleep while later cycles have a higher proportion of REM. By the final cycle, your body may even skip NREM deep sleep entirely. Overall, your body spends more time in NREM phases of sleep.
A couple of scary facts about lack of sleep:
- Routinely sleeping less than six or seven hours a night demolishes your immune system, more than doubles your risk of cancer.
- Insufficient sleep is a key lifestyle factor determining whether or not you will develop Alzheimer’s disease. Inadequate sleep — even moderate reductions for just one week — disrupts blood sugar levels so profoundly that you would be classified a pre-diabetic.
- Short sleeping increases the likelihood of your coronary arteries becoming blocked and brittle, setting you on a path toward cardiovascular disease, stroke, and congestive heart failure.
- Sleep disruption further contributes to all major psychiatric conditions, including depression, anxiety and suicidality.
- Too little sleep swells concentrations of a hormone (ghrelhin) that makes you feel hungry while suppressing a companion hormone (leptin) that otherwise signals food satisfaction.
Needless to say that a solid and solid sleep pattern and sufficient sleep is crucial for your health.
What can you do to improve your sleep?
- reduce caffeine
- reduce alcohol
- remove screens from the bedroom
- lower temperature bedroom
- regular bed and wake-up time
- go to bed only when sleepy
- never lie awake in bed — get up and do stuff
- avoid daytime napping
- mentally decelerate before bedtime
- remove visible clockfaces from your view
- don’t exercise just before bed — as body temperature and heart rate can remain high leading to worse sleep
The single most effective way of helping improve your sleep is to go to bed and wake up at the same time every day.