Sleep is the corner stone of optimal health in humans. Lack of sleep leads in almost all cases to an increase in all-cause mortality and an impaired immune system. Its therefore super important to not only to get good sleep duration but also better sleep quality.
There are two pathways to optimal sleep. The first is sleep pressure and the second is circadian. Let’s take a look at both of these pathways as both are super important to optimising sleep scores.
Sleep pressure is the need to sleep. During the day our mitochondria, which are the batteries in our cells, produce energy. This energy is called Adenosine Tri-Phosphate (ATP). ATP is produced in response to our body’s need for energy to perform a specific task. Whether its digesting food, breathing or running a marathon. The more active we are the more ATP we need to produce. Energy is released by hydrolysis of the third phosphate group in ATP.
When we produce ATP the adenosine from this molecule which remains after hydrolysis builds up in the cells of our bodies as a waste product. Adenosine is an inhibitor of sleep latency, which is our ability to fall asleep. In our brains Adenosine is an inhibitory neurotransmitter which inhibits wakefulness. Across the day Adenosine rises in the brain until such a point that a person will develop feelings of sleepiness.
During sleep Adenosine levels drop, which has led scientists to theorise that sleep is fundamental for clearing out adenosine from the brain. If you drink caffeine this blocks our adenosine receptors which causes us to feel awake. This is why many people who drink coffee 6-8 hours before bed will have trouble getting to sleep.
Every being on earth, including humans have circadian rhythms. A circadian rhythm is a 24-hour cycle of almost all internal processes in living beings. Circadian rhythms are endogenously generated but are entrained by environmental cues such as light and temperature.
Light and temperature have a unique relationship in initiating sleep. Human’s evolved their circadian rhythms tied to sunlight. When the sun rose in the mornings our circadian rhythms would be entrained and we would produce serotonin, dopamine and cortisol, three compounds required to start our days optimally. Light frequencies from the sun would change each hour sending new messages to the brain to release and suppress certain hormones. As the sun set and night fell darkness would signal to the brain to reduce cortisol and increase melatonin (sleep hormone). The red light from our campfires would relax us further and not interfere with sleep.
In our modern world we are surrounded by blue light. This light, in the form of LEDs now occupies the majority of our lives. From smart phones, TVs, Laptops, house lights, cooker light, fridge light, car headlights and shopping mall lights, we are now inundated with blue light. Blue light during the day tells our brains its daytime, blue light after sunset does the same thing, tells our brains its daytime. When our brain thinks its daytime, we do not produce melatonin which helps us get good quality deep and restorative sleep. So, when we go home after sunset and switch on the TV or house lights we are in effect telling our brains its daytime which messes up our sleep and circadian rhythms.
In order to optimise circadian sleep in our modern blue lit world we either need to sit in darkness with only red-light sources present, or wear blue light glasses. Blue light glasses with a deep amber lens that blocks 100% of light between 400 to 550 nm is essential according to the literature on sleep. BLUblox Sleep+ glasses are the go to for anyone looking to optimise their circadian sleep.
You might think you sleep okay, but if you want to optimise sleep then you need to look at perfecting the two pathways to sleep. One does not work without the other and what the body wants is deep, restorative sleep which can only be bought about by practicing proper light management after sunset. Wear blue light blocking glasses after sunset, quit caffeine after noon and experience a level up in your sleep, health and overall wellness.