The investigation about the sleep and the life, the people taking the sleep of 7-8 hours seems to live long most. We should pay attention to a point that the death rate of the people taking sleep of more than 10 hours is higher than that of the people taking sleep of 4-5 hours.

By the way, the sleep time that the life is shortest is less than 4 hours. In other words, we cannot live long even if a sleep is extremely short or long. It has some sense of incongruity that it is said that it is no use even if long, doesn't it?

But may you not oversleep for a long time on holidays, and rather have an experience of condition not appearing on that day all? It has sleepiness all day to take the sleep for a long time, and this is because an awakening degree lowers. Then a night sleep will fall into a vicious circle to become light.

After all I spend it getting up early in the morning actively in the daytime. That this brings a deep sleep; good; is circulated.