How does your body know when it is time to sleep?
There are two main factors that determine when you want to sleep and when you want to be awake. The first factor is a signal beamed out from your internal 24 hour clock located deep within your brain. The second factor is a chemical substance that builds up in your brain and creates a "sleep pressure". The longer you have been awake, the more that chemical pressure accumulates, and consequentially, the sleepier you feel.
These are the 2 factors that dictate how alert we are during the day and when we feel tired and ready for bed at night.
Let's talk about Rhythm, to be more precise the circadian rhythm. Everyone generates a circadian rhythm. The internal 24 hour clock within our brain communicates it's daily circadian rhythm to every other region of our brain and every organ in our body. This 24 hour clock helps to determine when we want to be awake and when we want to be asleep. But it also controls other rhythmic patterns. These include your timed preferences to eat, drink, your moods and your emotions, the amount of urine we produce, our core temperature, metabolic rate, and the release of numerous hormones.
My Rhythm Is Not Your Rhythm
Although every human being displays an unyielding 24 hour pattern, the respective peak and trough points are very different from one individual to another. For example some peoples wakefulness arrives early in the day, and they get sleepy early at night. These are "morning types" just like me. These make up around 40% of the population. Others are evening types and account for around 30% of the population, they naturally prefer to go to bed later and wake up later. The remaining 30% of people lie somewhere in between.
They are sometimes called morning larks and night owls.
Night owls very much dislike falling asleep early and they hate getting up early, They are unable to function at this time, despite being "awake" the brain remains in a sleep more like state in the early morning. This is especially true of a region called to prefrontal cortex, which sites above the eyes, and can be thought of as the head office of the brain it controls high level thought and logical reasoning, and helps keep our emotions in check. When a night owl is forced to wake up early, their prefrontal cortex remains disabled "offline".
An adults owlness or larkness is known as their chronotype and is strongly determined by genetics, there isn't much we can do about this. Sadly , society treats night owls rather unfairly. They label them for being lazy, because they don't wake up until later in the day, and most of the time this is because they didn't fall asleep until a lot later at night.
It is not the night owls choice to go sleep late, like it's not the morning larks choice to wake up early, this is most likely due to DNA hardwiring, it is not their conscious fault but their genetic fate.
Because of today's society, having to get up early due to work and school standards, most Owls are chronically sleep deprived, having to wake up early but not being able to sleep in the evening. Owls tend to burn the candle at both ends, increasing the risk of greater ill health, higher rates of depression, anxiety, diabetes, cancer, heart attack and stroke.
Which one are you?
Going forward, we should try make choices in our lives that accomodate our chronotypes, this will not only increase the chances of us being more successful in life but a lot healthier too.
In the next blog we will look into melatonin
The above information is taken from the book Why We Sleep by Matthew Walker.