Is it better to approximate the average number of persons in a (large) chat with a sine function or using a sum of normal distributions?

@Segebodo Sorry, maybe I should have added it. I am thinking about the graph for, e.g., seven days.

When plotting it, one can notice a something that looks like a sine-wave. But most people probably do not decide when they like to chat based on daylight, so there is no reason for it to be a sine.

It becomes even more complicated, when one assumes discrete events, like, e.g., a part of the people leaving exactly at 5pm instead of normally distributed around 5pm.