Wish to add one more reason here. This is not the case with metros only. Guys/girls away from home for career or studies and even parents whose kids are away from home are likely to be affected by insomnia.
One has to adhere to sleep schedule not to disturb body clock which affects routine activities. Think over it fast as soon as one detects symptoms of disturbed activities or sleepy feeling during day time. Prevention is always better than cure.
