The word combination ‘to go to sleep’ or even ‘fall asleep’ implies that sleeping is something you can easily control. We expect ourselves to switch off and on just like a light bulb.

In reality, sleep is a complex process orchestrated by hormones and chemicals and impacted by an external environment.  You can’t force yourself to sleep.

If you want to improve your sleep quality, you should understand what you are dealing with and how it works. In this blog post, I’m demystifying the magical process of sleep for you, so you start understanding your sleep – and yourself – much better.

Let’s look into the two systems that control our sleepsleep drive and sleep rhythm. Both have an equally significant impact on your sleep.


Sleep drive aka natural sleep pressure

The longer we are awake, the more we feel pressure to sleep. That’s why the sleep drive is also called natural sleep pressure.

Sleep pressure results from a homeostatic control system (homeostasis is the state of steady internal conditions) that reflects the natural accumulation of sleep-inducing forces when awake. Lacking sleep drive, we would not have the pressure to sleep, causing an imbalance in our overall physiological functioning.

The main sleep chemical in this process is adenosine. As it accumulates throughout the day, you get sleepier and sleepier. Adenosine accumulates in the forebrain and dampens our brain’s nerve activity. Hence we become fatigued.

Interesting fact – adenosine and caffeine are very similar molecules. This is why caffeine can disturb and interfere with the work of adenosine. You can read more impact of coffee on your sleep in the previous blog post – Three habits can improve your sleep.


Sleep rhythm aka your internal clock

Did you notice that you get sleepier at specific times of the day?

We tend to sleep and wake up in sync with the day and night cycle. Our body follows the natural sleep rhythm, also known as circadian rhythm or internal body clock.

In our brain, there is a highly light-sensitive mechanism – SNC (suprachiasmatic nucleus). SNC, our master biological clock, controls the timing, intensity, and duration of sleep through circadian rhythm.

That is why humans are most alert while the sun is shining and are ready to sleep when it’s dark outside. So don’t get surprised that you feel more tired and sleepy on a grey, gloomy day.

This sleep rhythm follows your body temperature. When the body’s temperature goes down, it signals your brain to release the melatonin hormone, the primary sleep hormone. The more melatonin you have, the sleepier you get.  Have you ever noticed how difficult it is to fall asleep in a hot bedroom? Now you know why – you have not enough melatonin! Therefore It is better to sleep in cooler environments (not hotter than 22 C).

Your circadian rhythm causes your level of wakefulness to rise and dip throughout the day. Most people feel the strongest desire to sleep between 1:00 pm and 3:00 pm (a.k.a. the post-lunch, afternoon crash) and then again between 2:00 am and 4:00 am, but this can vary. As it differs from person to person, some people really need an afternoon nap, while others never feel sleepy in the afternoon.

This rhythm can also change as you age. For example, when you were a teenager, your body needed to sleep for more and go to bed and wake up later.


So what now?

Now you understand that sleep is a very complicated process. It is not something that you do; it happens to you thanks to a well-orchestrated work of hormones and chemicals.

When healthy and exposed to daylight’s natural rhythms, both sleep rhythm and sleep drive work well together, and it is most natural for us to fall asleep a few hours after sunset and wake shortly after sunrise.

And as you probably experienced, this dynamic is easily disturbed by everything from seasonal light changes to caffeine to stress to travel to hormonal changes.

One of the best ways to start working on your sleep is to learn what causes your sleep disturbances. I created this free guide Getting a Good Night Sleep in 3 Nights, to reveal the #1 reason you don’t sleep well and solve it with 3 proven practices. Download the guide below.