Dr Mercola says.......
If you get up to use the bathroom during the night, please whatever you do, keep the light off. Even the tiniest bit of light in the room can disrupt your circadian rhythm and your pineal gland's production of melatonin and seratonin. As soon as you turn on that light in the bathroom, you will, for that night, immediately cease all production of the important sleep aid melatonin and this has been clearly shown to dramatically increase your risk of most cancers, but especially breast and prostate cancers.
Not a lotta peeps knows dat!