Why do we need to sleep in total darkness?

Why do we need to sleep in total darkness? There are many reasons why we must sleep in total darkness. One of them is relaxing our body muscle. After we got tired on daily, our muscle is in pain and needs to recover from that pain. The best way to recover is by having an effective sleep. Next, the interesting part why do we need to sleep in total darkness is to prevent from getting cancer. Do you know, if we sleep while switch on the lamp, the possibility to get cancer is high.This is because, even we close our eyes during sleep,our eyes nerve still can detect the presence of light. then it send an impulse to the brain to reduce our melatonin. Melatonin is important hormone secretes from our body. It can maintain our blood pressure, insulin, metabolism system and surely can reduce the risky on development of cancerous cells. So, to get the high level of melatonin,we should sleep in total darkness. Sleep healthy, Stay healthy., unless you want loss your precious life