In a May 2012 journal, Harvard University researchers reported on ongoing research to understand the range of health effects produced by increased exposure to light at night, especially blue light emitted by electronics, including smartphones and tablets.
According to the report, many studies have identified a broad spectrum of serious health concerns such as diabetes, heart disease, depression, and several types of cancer as being linked to nighttime light exposure, especially when such exposure is a daily work environment.
Exposure to light suppresses melatonin, which is a hormone critical to regulating circadian rhythms and sleep/wake cycles. Increased exposure to light is part of the reason so many report poor sleep. Moreover, blue light, which is emitted by many electronics and energy-efficient bulbs, suppresses melatonin for almost twice as long as incandescent lights. In short, the quest for energy efficiencies in lighting will have a significant effect on health unless some adjustments are made. Some options are:
-Use incandescent or warm tone lights for evening reading. Avoid LED’s, especially those with a lot of blue light.
-Avoid using electronics or working night. If you must, wear blue-blocking glasses, such as Slumber Shades.
Everyone should be alert to unintended consequences from the benefit of light in the evening. Energy efficiency savings are significant for everyone, but using them should not cost your health.
See: Blue Light Has a Dark Side http://www.health.harvard.edu/newsletters/Harvard_Health_Letter/2012/May/blue-light-has-a-dark-side