Why are so many stars insomniatic?

Aly and Aj, Kiely of the Cheetah girls, Hilary Duff (She has OCD about cleaning. She can't sleep if theres a mess of any kind in the room. Hotel managers like her :) Aly and Aj even made wrote a song and titled their album "Insomniatic" it's so weird! Is there some kind of trend or something we all are missing?