We know from experience that workplace accidents and worsening illnesses are more likely to occur at night. The number of car collisions peaks around 3 am. Toothaches often peak around 9 pm. And it is also at night that horrific, catastrophic events like the Chernobyl nuclear accident are more likely to occur. It is gradually becoming clear that the body’s “circadian rhythm” (internal clock) is involved in these accidents and illnesses. For example, the human immune system responds more strongly at night, which is the natural time of sleep. It responds more strongly to eliminate bacteria and other things, and works to protect people.
Some people aim for zero risk. One of them is the tendency to be clean. There are people who wash their hands and gargle to completely block pathogens. However, it seems that the weakening of the immune system due to modern people’s tendency to be clean is becoming a problem. For example, food poisoning caused by enterohemorrhagic E. coli O157 has occurred. This O157 cannot develop in dirty places, but only in places where cleanliness is taken too far. O157 has developed in countries that are too clean, and because of the development of O157, an ironic cycle has been created in which sterilization efforts are now being implemented in earnest. One of the problems in clean countries is the increase in allergies such as atopic dermatitis and hay fever. Being in a sterile environment weakens the immune system and makes people weak against bacteria. People with diverse immune systems have the strength to survive. On the other hand, people in a sterile environment seem to become weak against the environment. Excessive cleanliness can actually cause various health problems.
Hand washing and gargling are necessary, but if being too clean is also a problem, what actions should we take? The conclusion seems to be that we just need to boost our immunity. It is said that a good night’s sleep is effective in boosting immunity. So what should we do to get a good night’s sleep? The quality of sleep is also greatly affected by temperature and humidity. It was found that people who stayed in a room with a temperature difference walked about 1,400 fewer steps per day. Conversely, people in a room with no temperature difference tended to exercise more. Increased exercise stimulates the secretion of serotonin, which at night becomes melatonin, which promotes sleep. Exercise stimulates the secretion of serotonin, which in turn leads to good sleep. Children who exercised more had a lower rate of absenteeism and a lower incidence of influenza.
