One of the main stress hormones, cortisol, has a circadian rhythm. This means that the concentration of cortisol in the blood varies according to the time of day. At nighttime, cortisol concentrations in the blood are low. When working night shifts, our body is fighting sleep. A recent study shows that working at night is associated with a more important increase in daytime cortisol levels than usual.
Bedtime is the first moment of the day where our brain is not stimulated. Thus, the brain does not like to stop being stimulated. This is why before bedtime, most people will start ruminating about their day and it becomes impossible to fall asleep. To overcome this situation, it is recommended to take one hour per day without any stimulation, for example, by walking the dog, by knitting, by swimming or running. This way, the brain will be without any stimulation and it will be possible to think about the events that occurred during the day and it will be much easier to fall asleep.