Ask Dr. Nandi: Why does blue light affect our sleep?

Posted at 1:51 PM, Sep 12, 2018
and last updated 2018-09-12 14:09:48-04
As summer is winding down and the sun is setting earlier, we’re using more indoor light before bedtime.  And that can lead to problems with sleep.  Because artificial light can throw off our body’s biological clock, especially if it’s blue light. 
Question: What is blue light?
Blue light is very bright and emits blue shorter-wavelengths.  This type of light is quite popular because it’s energy-efficient.  Now using blue lighting during the day is great as it helps boost our attention and our mood.  But that’s not what we need in the evening hours before bed.  And it’s not just indoor lighting that we need to be concerned about, it’s also the blue light coming from our favorite digital devices that are never far from our hands, like our smartphones and tablets. 
Question: So why does blue light affect our sleep?
Research shows light of any kind can suppress melatonin.  But blue light in particular can damage our sleep as its very powerful at delaying our body’s ability to secret this drowsy-inducing hormone.  So now you’re awake later than usual and this messes up your body’s internal clock.  Basically you end up resetting it to a later schedule.  So not only do you get less sleep, but the quality of your sleep can also be affected.  Even if you sleep for 8 hours, you can still wake up feeling tired.  And what’s also really concerning is how research has linked exposure to artificial light to cancer, heart disease, weight gain and depression.  
Question: With kids back in school, many are on their digital devices at night, what advice do you have for parents?
As a parent of a teenage daughter, I know that teens love their devices.  But they need their sleep, at least 8 hours.  Otherwise they can struggle with concentration, poor grades, anxiety, aggression, inappropriate behavior, even suicidal thoughts. So I’d recommend that teens are given a digital curfew where they turn off digital devices 1-2 hours before bed.  If that’s not possible, try blue-blocking glasses or use an app that filters out blue wavelengths.  And that way their bodies can begin making sleep-inducing melatonin and they’ll get the sleep their bodies need.