How does our body know when to get sleepy?

Every morning after a good night's sleep, I wake up feeling so good. I've always wondered how our body knows when to get sleepy in the evening. How does it know not to feel sleepy during the day?

Firstly, it would be weird if everyone starts getting tired throughout the day. Teachers would be falling asleep while teaching and cab drivers would have to stop by the side of the road to take a snooze. Thankfully most of us go to sleep when its dark at night and not at random times of the day.

Our Wonderful Brain

I'm so amazed at how our brain works. Other than thinking and controlling the movement of our arms & legs, our brain also performs what my dad calls 'automatic' functions, or simply actions that doesn't need us to think in order to get them done. Some examples of these are: breathing, hearing, seeing and... you guessed it, sleep.

From the moment we wake up, our brain slowly lets out a chemical that is builds up in our head until it fills up by evening, this is much like filling up our water bottle at the water cooler. We slowly feel sleepier as this chemical builds up, and that's what makes us tired in the evening. As we sleep, our brain actually absorbs all the chemicals back into storage, and we wake up with our tank at zero. Pretty neat!

How much sleep is enough?

That explains why we need a certain number of hours of sleep. If we wake up say halfway during the absorption process, our 'bottle' isn't empty and fills up pretty fast, causing us to feel sleepy during the day. In the same way, if we take a nap in the afternoon then there isn't enough chemical in our head to make us feel sleepy at night.

The next time your parents tell you its time to go to bed, get going!