The below text is adapted from the book, the Science of Sleep (Author : Heather Darwall Smith, June 2021). Its a game changer for anybody who wants to perform at their best, sleep is the No. 1 activity to engage, before nutrition and before exercise.
Without a good night's sleep, we can behave like "The Walking Dead" devoid of any logical, emotional nor cognitive thought. How many hours we need each night ? Well like they say in the movies, "the jury is still out" on this but most people need 7 hours on average. Some need only 5 hours and some need 9 hours, so this varies from person to person, as well as the age of the person.
The Sleep / Wake Cycle
Our sleeping and waking hours are regulated by 2 Biological Processes that work in tandem. Our Circadian (circa Latin "about" and dies Latin "day") rhythm. The circadian rhythm also known and Process C regulates our sleep as well as numerous biological functions of our body. Better known as our 'Body Clock', the rhythm keeps our body in-sync with the day, our moods, our sleep and our energy. Its like a sinusoidal cycle with one peak an one valley every 24 hours.
Our homeostatic sleep pressure, or Process S defines our urge to go to sleep. The longer we stay awake, the greater the build up of this Sleep Pressure or urge to go to sleep becomes.This build up as far as we know, is due to the accumulation of the chemical called adenosine. This chemical which is naturally secreted in our bodies (unless you have degenerative brain diseases like Parkinson's or Dementia). Adenosine build up causes drowsiness and hence we fall asleep. The rise and fall (or Cliff Effect as shown in the picture above) is called Process S and it supposedly occurs EVERY SINGLE DAY.
This rise and fall of the sleep pressure is called the Homeostatic Process. or Process S. Process S looks like a Cliff rising from the low in the morning at 7am (almost no adenosine) till about 11pm that same evening.
Wait, not so fast.
Process S by itself is not sufficient for anyone. It needs to coordinated with our Circadian ryhthm, or Process C. This ryhthm is like a sinusoidal curve, peaking at around 2pm, and then gradually drops down - way down till our energies are at their lowest at around 11pm. The "Sleep Gate" or the doorway to the Sleep Zone opens. Therefore, our Sleep Clock is in fact the interplay of 2 Graphs, the Homeostatic Process and the Circadian Cycle. At roughly 11 pm of our local time - wherever we live at for a prolonged duration of time - 2 things happen AT THAT TIME.
a) The Process S Homeostatic Process where the adenosine levels are at their peaks, and hence the drowsiness of the person is at his peak.
b) The Circadian Rhythm is at its lowest, and the Sleep Gate is right at the bottom, and opens, hence triggering the sleep inducing hormone Melatonine. Your energy levels will first stabilise, and then build up as you sleep.
As morning approaches, Process C triggers the Alertness hormones Norepinephrine, which are essentially neurotransmitters in our brains and spinal cords. Norepinephrine increases alertness, arousal and attention and is so crucial for everyday functioning.
Hence the 2 Graphs ideally must work in Unison for anyone to be at his best during the day.
Regulating the Sleep / Wake Cycle - a Neurotransmitter called Orexin
The mechanisms which move us from wakefulness to sleepiness and then sleep is known as the 'flip-flop' switch. A system that controls the brain circuitry via 2 nerve cell groups. One group wakes us (the Norepinephrines) and the other sends us to sleep. The flicking of this On-Off switch between wakefulness and sleeping is controlled by this neurotransmitter called Orexin.
If this neurotransmitter Orexin is damaged by brain injury or Orexin levels are too low, such as those with Narcolepsy, the ability to move between sleep and wakefulness becomes unstable leading to a range of sleep disorders which can be potentially life threatening or diminishing one's quality of life severely.
Before Seizing the Day I need to Seize the Night First !
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