Even the tiniest bit of light can disrupt your pineal gland’s production of melatonin and serotonin, thereby disrupting your sleep cycle. Even the tiniest glow from your clock radio has the potential to interfere with your sleep.
So, close your bedroom door, get rid of night lights and use blackout shades or thick drapes. If shades are out of your budget, use a well-fitting eye mask.
Refrain from turning on any light at all during the night, even when getting up to go to the bathroom. If you absolutely have to have some sort of night light, use a red bulb.1Sleep — Why You Need It and 50 Ways to Improve It