Scientists have discovered that sleeping well enough to lower your blood pressure or prevent it from increasing may require total darkness. The purpose of this study was to determine how light at night affects the health of older adults. Researchers analyzed data from 552 participants in the Chicago Healthy Aging Study, ranging from 63 to 84 years old. During the course of the study, participants wore a device that measured light in their bedrooms, as well as general health metrics like blood glucose, blood pressure, cholesterol, and weight (including obesity). Researchers are still examining the connection between light during the night, circadian rhythms, and overall health, but even if nothing else, this is another reason to make your bedroom a sanctuary for restful sleep. A cool, dark, and quiet bedroom is essential.