Lights out means lights out. Avoid using your cell phone, computer or television at least one hour before bed. When you do decide to sleep, turn off all of the lights.
If you go to bed earlier than the rest of your household and light still peeks in through the cracks of the door, purchase draft snakes to block out the light.
Draft snakes are typically used to control outdoor air from entering the home but it can be used for the purpose of eliminating light from entering as well.
Light exposure limits the amount of melatonin, a sleep hormone your body releases, which means it takes longer for you to fall asleep.