Prior to the technology boom of the late 70's, early 80's there was an oh so convenient stoppage of television with a siren and black and white screen or the very well known fuzzy static. In addition, computers were not mainstays in the home; not to mention laptops and tables. Oh! And supermarkets actually closing times. We would prepare for bed not too long after the sun bid us a pleasant adieu, because, well . . . there was nothing to do. Good sleep hygiene was not yet thought of, because the routine of preparing for sleep was a normal part of life.
First, let's have a conversation about melatonin. Melatonin is significant for its effects on our mood, immune function, circadian rhythms, and the quality and quantity of our sleep. Melatonin is known as an anti-aging and anti-stress agent because it both suppresses cortisol and is a powerful antioxidant. The production of melatonin by the pineal gland is activated by darkness and inhibited by light. Once released, melatonin circulates through the brain via the cerebrospinal fluid (CSF) and enters nearby blood vessels for distribution to the rest of the body. When melatonin levels are disrupted, people can experience mood swings, depression, and seasonal disorders.
Enter the early 90's (cue Darth Vader's theme music). Internet! Computers in every home! Video games! Tablets! Smartphones! When you have stuff to play with, why not play with it right? While any kind of light can suppress the secretion of melatonin, blue light at night does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours). All of the aforementioned technological marvels use blue back-light for illumination. So . . . I hate to nag ya, but no new age technology 2 to 3 hours before bed (sigh, this is very difficult) Need we discuss further?
Better Sleep is a Better You!
https://www.health.harvard.edu/staying-healthy/blue-light-has-a-dark-side