Saturday, March 4, 2017

Screen Time Blues

In the previous post a brief explanation of melatonin and cortisol was given to help give an explanation to the origin of our sleep cycles. In this post I am not going to give a lecture on when you (and your family) should and shouldn't view computer/TV/smartphone screens for optimal health. This post a a brief explanation simply of what screens do to the brain, notably in the later evening. Hopefully you can derive what is best for you and your family as far as time to view screens from these few brief points regarding screens and the brain:



  • Blue light is really the worst part of the spectrum when it comes to inhibition of the release of melatonin, which is the hormone that assists you to fall asleep. Research done by two different groups in 2001 found not only that blue light was the greatest inhibitor of the release of melatonin, but also found that blue light from LED sources (the source of light on all electronic devices now) is the blue light causing the greatest problems with the release of melatonin.
  • There are a few answers that have come to attempt to allow one to use screens while being able to prepare one for bed. iOS 9 was the first smartphone system to introduce a preset time of day at which the screen would shift you a very yellowish source of light--Night Shift. Prior to this the original investors of Picasa created a program called f.lux in which you can have your computer screen set to do the same idea--remove the blues and violets by changing any whites to a beige/yellow. This program can still be downloaded and used on Macs and PC's. 
  • Another approach (that is far more simple) just involves the reduction of the brightness of a screen. A reduction in brightness ultimately results in a reduction of blue-light photons reaching the photoreceptors that communicate with the melanopsin-containing ganglion cells which then inhibit the release of melatonin.
  • In this interesting interview with a pair of researching professors in the field, they simply state that screen time in the hour prior to going to sleep results in:
    • Taking longer to fall asleep.
    • Less amount of REM; this results in less time dreaming
    • A greater degree of sleepiness after an 8-hour sleep
    • Greater difficulty waking up after an 8-hour sleep
  • Just as white light (which has a greater concentration of the blue wavelengths resulting in it being white vs. the classic yellow colour of an incandescent filament) can be seen as having a negative affect upon those who can live and work with a consistent schedule. On the bright side, those who have rotating shift work, or those who frequently travel great distance via plane in which they quickly want to alter their circadian clocks can use the blue light from such devices to alter their circadian rhythm at a faster pace.  
  • While a myriad of different papers have been written regarding the decrease in the average amount of sleep by teenagers since the introduction of the smartphone, the key point to all of them is that smartphones have reduced the amount of sleep by teenagers (on average). This reduction is sleep will result in slower formation of the prefrontal cortex, and lesser amount of content being kept in the long term by passing through the hippocampus. The key point is that while the numbers and controls in that various papers may be different, all agree that there is no benefit to our sleep with exposure to screens, notably in that last hour before we plan to go to sleep. 

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