One effect that watching a bright screen right before bed has is that you don't get tired enough to sleep. Before you go to bed, your body has to wind down properly. So, exposure to blue light means that instead of producing the hormone melatonin, which basically puts you to sleep, your body ends up releasing cortisol.
Cortisol is often called the "stress hormone" because of its connection to the stress response. Cortisol is a steroid hormone that is produced by the adrenal glands. When released into the bloodstream, cortisol can act on many different parts of the body and can help your body respond to stress or danger and increase your body's metabolism of glucose.
Avoid looking at bright screens beginning two to three hours before bed because here’s what happens: using TVs, tablets, smartphones, laptops, or other electronic devices before bed delays your body's internal clock (a.k.a., your circadian rhythm), suppresses the release of the sleep-inducing hormone melatonin, and makes it more difficult to fall asleep.
As for blue light, research suggests that progressive destruction of light-detecting cells in the eyes due to prolonged exposure to blue light could contribute to age-related macular degeneration, which is a leading cause of blindness because it is known that blue light harms vision by damaging the eye's retina.
If you're spending a lot of time each day in front of a digital device, blue light filtering glasses can help protect your eyes and prevent eye strain. Remember, damage from blue light is cumulative, so the more time you spend in front of screens without protection, the more likely you are to experience problems down the road.
Most modern devices have a night mode feature which, when activated, helps reduce blue light and overall screen brightness which can affect your sleep and eyes. By using this mode on all your devices, you reap quite a few benefits.
For computer users there are screen shields that can be ordered on line and Windows 10 users can activate the built in blue light filter. Also, there apps that can be downloaded. One free, small version is called Iris Mini.
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Blue Light And Your Eyes