[56a middle] Rava: Cohabitation is normally performed at night, but it is also permitted during the day, if in a darkened house.
R’ Rosner: Having a darkened room helps to keep our focus less on the physicality of the act itself, and more involved in the connection between husband and wife.
D-E-ep Thoughts: When it comes to actions involved in intimate areas, it becomes easy to lose our spiritual focus. The Torah helps guide us with ‘best advice’ practices to help maintain a holy agenda. If we follow Hashem’s words, we will continue to lead the happiest and most fulfilled lives, both in this world and the next.