Have you ever wondered why you fall asleep at night ?

Current science isn’t really sure what makes us fall asleep, but there are some theories that have been proposed in recent years.

For today's blog post, we will focus on one of those theories. The theory is based off the idea that the byproduct of energy makes us fall asleep. To me, this makes perfect sense because I tend to sleep much better on the days when I exercise versus the days I don't. But why does this happen? How does exercise impact our sleep? To understand this mechanism we must take a couple steps back and discuss how the body makes energy. In order for your body to move and work properly the body creates an energy molecule called adenosine triphosphate (ATP). We all remember learning about this molecule called ATP right? The best way to understand how this molecule works is to think of it as a currency. For example, when you go on a walk or have a meeting you are using ATP to move and talk to your co-workers. It is responsible for everything, and without it your body and mind would be useless. But like most things in life, there is a cost to pay and ATP is no different.

If you want to use this energy the body must break ATP down into another molecule called adenosine diphosphate (ADP) which then gets broken down into adenosine monophosphate (AMP) and finally into adenosine. Once this occurs, the adenosine molecule crosses the blood brain barrier and latches onto the brain receptors. This process occurs throughout the day and is increased during exercise due to body's need for energy. Your muscle's rely on ATP for movement, therefore exercise will increase the buildup of adenosine in the brain. As the adenosine builds up, it signals to the brain that your body needs rest to recover. Once the adenosine hits its threshold in the brain, you begin to feel sleepy. This feeling of fatigue is known as sleep pressure.

The body relies on this sleep pressure signal to function properly. Adenosine is a metabolic waste and can be very damaging if it is not cleared out. Every single reaction in your body has a good and a bad effect and adenosine is no different. Remember, *there is no biological free lunch, everything needs time to recover and our energy systems are no different. On the days when you exercise you will exert more energy. This exertion of energy will increase adenosine levels in the brain. This increase of adenosine will not cause much damage in a day. However, if it occurs on a frequent basis then you will be at a higher risk for brain damage and a shortened lifespan. The only way to recover from exercise and excessive adenosine build up is through sleep. Your goal should be to fall asleep between 830pm to 11pm and to sleep for 7.5 to 9 hours per night. I know it sounds like a lot of work, but there are certain things in life that are non-negotiable and sleep is one of them. If you neglect your sleep, then your body will neglect the need to recover. It is as simple as that.