from within or outside the household. Complete darkness isn’t necessarily desirable: a dim nightlight can make the room more comfortable for younger children.
Children and teens generally sleep better in a room that is cool, but not too cold: temperature extremes in either direction may make sleeping more difficult. Temperature can become especially important in circumstances when families lack options to make the environment more comfortable: e.g., blankets, comforters, or adequate room heating in cold temperatures; fans, air conditioning, or open windows in hot temperatures. Sometimes, concerns about family security trump physical comfort, such as when families keep windows of bedrooms without air-conditioning or fans closed in hot summer months to deter crime.
Changing specific features and practices associated with the sleep environment is generally part of the strategy of health-care providers to improve sleep. Keeping noise, light, and temperature in mind, a “sleep friendly” environment is generally one that is cool, dark, and quiet.