What Is Sleep Quality?
We know instantly when we've had a bad night's sleep. We feel it. Despite getting in your usual quota of hours, you wake up feeling rubbish, sluggish, and lethargic. So, if sleep quantity is not the only determinant of good sleep then what are the hallmarks of it? The Sleep Health expert panel found that factors affecting quality sleep as:
You are asleep 85% of the time you spend in bed
You can fall asleep within 30 min of going to bed
You are aware of only waking up once per night
and, when you do, you fall back asleep within 20 minutes or less
Restorative Value of Sleep:
Today we have devices that can help us measure what it is happening during those hours we spend tossing and turning. Sleep quality is calculated by the:
1. Amount of time spent in bed.
2. Amount of time spent in deep sleep.
3. The consistency of the sleep - meaning how well you cycle through the stages of sleep.
4. Amount of times you are fully awake in the night.
A Little Sleep Science
A single sleep cycle is characterised by periods of rest that occur in chunks of 90-120 minute cycles comprised of 5 stages of reduced brainwave frequency throughout the night. This carefully curated sleep architecture ebbs and flows through two distinct periods, non-rapid eye movement (NREM) followed by rapid eye movement (REM) which is then sub-divided into four stages. Following a general slowing down in activity, referred to as the pre-sleep alpha brainwave state, stage N1 begins, also known as light sleep, the alpha brain activity drops to 50%.
Stage N2 is characterised by intermittent alpha and theta waves where K complex and sleep spindles are formed, the breathing and body temperature reduces to settle and prepare for N3 and N4. Slow-wave sleep or delta sleep (N3 and N4) is the most restorative as muscle tone is relaxing, the prefrontal cortex (responsible for analytical thinking) is switched off, breathing is periodic, and our body temperature is lowest. From here we transition to REM; while our muscle tone is completely relaxed our visual brain centre is active, allowing for dreaming as our brain rapidly saw-tooths through the range of waveforms. We will briefly wake up between each cycle but how robust our sleep is determined by how quickly we fall back asleep. It is normal for us to wake up as long as 20 minutes at around 4 am because melatonin production drops off. When we fall back asleep after 4 am, we will predominantly have light sleep and dreaming sleep, REM till the alarm goes off.
We will spend approximately 25% of total accumulated sleep in REM sleep and about 75% in NREM sleep (of which between 15-30% of the time is in a deep sleep, N4). However, this varies between individuals depending on our sex, age, chronotype, or hormonal balance. Unfortunately, as we age, the amount of deep sleep decreases. Research now shows that in order for our brain toxins to be flushed out and our body to efficiently be restored, we need to transition through 5 sleep cycles per a 24 hour period. The golden 'good sleep' in tantamount good health and wellbeing. It is also now being referred to as the fountain of youth - that time in our lives when we were robust, full of energy, and bounced to the beat of your own drum.
Five Tips to Boost Restorative Value:
Now, with busy demanding lives, we are hard-pressed to make the best use of our time. If you're anything like me, you'd rather be doing something more meaningful than wasting time wrestling the hot pillow. Techy scientists are mad for finding ways to boost deep sleep, here are some fail-safe evidence-based ways to ensure the precious deep sleep is not been interfered with:
Kill caffeine after lunch! Caffeine stays in your system for 12-14 hours and destroys the sleep architecture and our ability to get deep sleep.
Supper for Super Slumber! Eating food that helps produce melatonin, the sleep hormone is a proven way to support the body's harmony. Foods high in Magnesium, tryptophan, and B6, serotonin such as pumpkin seeds, chia seeds, kiwi, cherries, turkey, and greens are a winner!
Blue Block after Eight O'Clock! The light-dark cycle controls cortisol and melatonin production. Artificial light is high in the blue end of the light wave spectrum which wards off melatonin and promotes cortisol, the stress hormone. Research shows there is a one hour phased delay of melatonin release after looking at your screen at night - which may explain why you're tossing and turning.
Prepare your mind to rest! If you live a high-performance lifestyle, more so than ever you need to systematically dial down your engagement with the environment. Start with reducing sensory stimulation to 80% one hour before you plan to go to sleep to about 20% just before sleep.
Hack Deep Sleep! Techy scientists are mad for finding ways to boost deep sleep and have begun developing some interesting devices that mimic the deep sleep state in order to prolong it. The App Sonic Sleep uses sound waves https://sonicsleepcoach.com/, the Zeez Sleep Pebble uses the same electromagnetic pulses of sleep architecture throughout the night in order to encourage robust cycling through the sleep stages smoothly http://www.zeezpebble.com/en/welcome/, and there's also the Philips Sleep Headband to try out https://www.usa.philips.com/c-e/smartsleep.html.