Why is it so hard to fall asleep, even when im physically exhausted?

Insomnia: Sleep onset insomnia is a common issue in many people. It has many causes and needs to be evaluated. Over time it can have health implications. Sleep onset insomnia can portend severe underlying medical issues, after a complete sleep history and physical by a specialist, you may be prescribed meds, cognitive based therapy or may in fact need a sleep study depending on what is found.