Today's bedrooms have to admit that they are often overwhelmed by the small lights of electronic devices, computer monitors, handheld radios and smartphones, and so on. What science is trying to tell us is chronic exposure to night light that leads us to a series of health problems.
To understand why chronic exposure to night light is so severe, we must consider human evolution. Today we have artificial lighting at night. This internal illumination is much less powerful than sunlight, but nevertheless many orders of magnitude higher than star and moonlight, a change that affects a series of biochemical reactions related to the frequency of light, including cortisol production and melatonin.
Melatonin suppression is key to understanding a lot of why these lights are bad for us. This biochemical compound is produced by the pineal gland of the brain at night, when it is dark, to regulate our sleep-wake cycle.
It lowers blood pressure, glucose levels and body temperature, the physiological responses that are primarily responsible for restful sleep. These cells respond to light and dark signals. The optic nerves in our eyes perceive light and signal, telling the brain that it's time to wake up. These signals also initiate other processes, such as increasing body temperature and producing hormones such as cortisol (stress).
Our cortisol levels are relatively low at night, allowing us to sleep, and higher during the day, allowing energy levels to stabilize and immune function to be modulated.
