ABSTRACT
Human sleep across the 24-hr day and human performance during sleep deprivation are sensitive to the effects of environmental conditions. Scientific evidence demonstrates that the brain sensory systems are active during sleep. Environmental factors such as noise, odors, temperature, and bed partners can negatively influence sleep. Exposure to altered or extreme environments such as urban noise, medical intensive care units, altitude, and space flight also disrupt sleep and may lead to chronic sleep loss. Ambient light levels influence human performance during sleep deprivation, but the influence of other environmental factors on human performance during sleep deprivation has not been well characterized. Humans have gone to great lengths to improve the sleeping environment. There is often an environmentally controlled room in the home with a bed surface dedicated to sleep. It has been recommended that the optimal sleep environment is a quiet and dark room that is well ventilated and temperature controlled. The mattress should not be too soft or too firm, and the pillow should be at a comfortable height and firmness. Pets or the need to care for other people should not interrupt sleep. These recommendations form the basis of sleep hygiene, a basic tool used in clinical sleep medicine. Currently, there is experimental evidence to support some but not all of these recommendations.
