Hi,Thanks for query,
is natural and normal so do not become panic.
Now a days due to easily available sex literature and exciting movies and tv programme this habit is very common.
There is no bad effects on health.
But I will say that Every thing excess is always to be avoided.
Try to avoid sex movies,videos or porno.
Remain busy in your work whole day so that you may not get sex thoughts and will have good sleep.
Ok and bye.