How Do We Figure Out When We’re Tired?

We all know that we need to sleep in order to survive, but why is this the case and just how exactly do we know when we’re tired enough?

How Do We Figure Out When We’re Tired?

We all know that we need to sleep in order to survive, but why is this the case and just how exactly do we know when we’re tired enough?

Despite all of us spending roughly a third of our lives asleep, science has yet to truly grasp exactly why this is the case. Sleep is one of the eternal constants across all organisms that possess a nervous system, and still its true purpose remains shrouded in mystery.

However, recent findings from the Bar-Ilan University in Israel may have shed some light onto the conundrum.

So What New Information Has Been Discovered?

The research revolves around the sleep habits of zebrafish, but the results have also been supported by some emerging evidence in mice. The research team worked off the hypothesis that tiredness can be defined by homeostatic sleep pressure. This pressure builds up throughout waking hours and decreases during sleep. But what precisely causes this pressure?

Well, the team discovered that neurons in the brain accumulate DNA damage while the subject is awake. Extremely high levels of this DNA damage can be dangerous, so the brain requires a “circuit-breaker” to facilitate healing. This comes in the form of sleep.

As DNA damage increases, so too does the need for sleep. The scientists discovered a maximum threshold for this sleep pressure, at which sleep became triggered for the zebrafish under surveillance. The sleep then started the DNA repair process, lowering sleep pressure for the next day.

Do We Know Any More About The Drivers of Sleep?

We certainly do. 

The researchers identified a protein called PARP1 as one of the first parts of the DNA repair process to respond. As a result, the expression of PARP1 can act as a mechanism to tell us when to sleep. These results were backed up when the team inhibited the protein in a study on mice. When the protein was blocked the mice didn’t become aware they were tired, didn’t go to sleep, and never entered the DNA repair process.

While these processes certainly don’t explain the entire sleep process, they definitely deepen our understanding of our evolutionary need to sleep. Studies like this are virtual in understanding such a complex process and could have a huge impact on solving the mysteries behind certain sleep-related neurodegenerative disorders.

You can have a look at the research paper here.

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