Hi Saurabh Sharma
Welcome to HealthcareMagic.
or lack of sleep can be due to many reasons .Most commonly it can be due stress
, fear , work tensions in daily life.There can be some psychiatric disorders also associated with this:Lot of drugs cause lack of sleep.
I advise you to visit your Physician and get evaluated if there is any underlying cause.
You should also practice yoga , meditation
with theta waves to reduce stress and enhance sleep.