Ever felt more tired after a strenuous day than a lazy day? There’s new research showing a connection between a greater need for sleep after a strenuous day than compared to a day where you could relax and not work. There are two main processes that drive us to go to sleep. The first, and most well understood, is the circadian rhythm where our 24 hour body clock keeps us in check via timed melatonin releases in correspondence to the amount of light in either day or night. The other is the homeostatic system, which causes us to feel tired after a long day or sleepless night.
The research team from the University College London (UCL) conducted the study using zebrafish larvae and influenced their brain activity using various stimulants including caffeine. Zebrafish larvae were chosen as they are commonly included in biomedical research due to also requiring sleep at night, like humans.
The team issued some zebrafish larvae caffeine to promote brain activity intensity and found that those given the caffeine ended up sleeping longer than those who were not given the caffeine. Researchers conducted another experiment that made the fish be more physically active through the night by showing them moving stripes, similar to fast flowing water, to make it seem like the fish had to remain swimming forward. Those being forced to swim during the night had more activity in the brain region that is active during sleep (much like a human’s hypothalamus) in the following sleep than those who were left alone.
The importance of this research provides further explanation as to why after a more mentally demanding day, we are more in need of sleep in comparison to a day off from work. Furthermore, it sheds light as to why people who suffer from seizures feel so exhausted after an episode. This same discovery can be applied to animals who avoid sleep under certain conditions, eg: starvation or mating season, by minimizing their brain activity.
Source: https://www.sciencedaily.com/releases/2019/09/190916110556.htm
