Nedra Jack January 3, 2019

Staring at blue light emitting screens on television, desktops, laptops, tablets, and phones before bedtime disrupts your sleep. In addition, the infographic below illustrates the effects of this disruption. Moreover, screen time resets your internal clock, known as the circadian rhythm.

Most of all, biological clocks are specific molecules (also known as proteins) found in every tissue and organ. While, the master biological clock is a group of about 20,000 neurons located in a structure called suprachiasmatic nucleus (SCN). And the SCN is located in a region of the brain called the hypothalamus.

Most noteworthy, the SCN receives direct input from the retina.  And, the retina is located in the back of your eyes. Furthermore, the innermost layer of the retina contains a tiny population of light-sensitive cells called melanopsin cells. Moreover, proteins called arrestins stop most retinal cell activity seconds after lights are turned on.  However, arrestins cause melanopsin cells to continue producing melanopsin proteins as long as light is present. As a result, the SCN continues to be notified that lights are on.

Above all, the SCN controls melatonin production. And melatonin is a hormone that makes you sleepy. Moreover, the SCN receives information about any light from the retina. So, with low light, and usually around 9 PM, the SCN tells the brain to produce melatonin for you to feel drowsy. However, after 10 minutes of light exposure, melanopsin signals from the retina causes the SCN to suppress melatonin production. As a result, the sleepy effects of melatonin go away.

Most noteworthy, the biological clock not only produces circadian rhythm but also regulates its timing. As a result, staring at screens prior to bedtime, causes the biological clock to affect your circadian rhythm. And disruptions in circadian rhythm are tied to sleep disorders, diabetes, depression, cognitive dysfunction, cancer, obesity, insulin resistance, and metabolic syndrome.

In fact, a 2015 study reported that screen exposure before bed caused a 13% to 52% increase in needing over one hour to fall asleep. In addition, countless other studies report similar effects of screen time on later bedtimes or less restful sleep. On the other hand, curtailing screen time two hours before bedtime has been reported to minimize sleep disruptions and result in good sleep.