There have been several news stories and political movements recently to delay school start times for teenagers.

The stories inevitably start with the fact that when children reach the age of adolescents, they have a shift in sleep phase and need to stay up later at night and get up later in the morning. They all seem to have a disorder called Delayed Sleep Phase Disorder.

This premise that we need to change school start times for high schools has kind of bugged me a bit, but I figured I was just getting curmudgeonly in my middle-age. In my day, kids, we went to bed at a reasonable hour on school nights and got up in the morning to head off to class, ready to learn.

While there is some truth to the idea that kids naturally shift to a somewhat later sleep schedule when they become teens, there is something much bigger going on here in our modern society. It is not a new "disorder" that suddenly everyone has - it is simply the effect of blue light at night on the circadian system. (Read the background science)

First, let's look at the stats:

The CDC reports that 72% of teens are not getting enough sleep (8 - 10 hours for 13 - 18-year-olds). (study)  

A study done by teenagers places the blame for the lack of sleep on too much homework. The teenagers also didn't think that their sleep deprivation had to do with social media use. (study)  Yes, my curmudgeonly self is thinking 'yeah, right – too much homework...'

Research studies, on the other hand, tell a different story.

A 2016 study in the journal Sleep looked at the effect of blue light on melatonin suppression in teens and young adults. Of the 71 study participants, those who normally stayed up later all had a stronger response to blue-light at night. In fact, the study found that all of the participants with later sleep timing were more responsive to blue light. The conclusion: "Blue light-sensitive young individuals are more prone to delayed sleep."

A 2017 study in the journal Sleep Medicine had a similar finding. The study participants were 28 young adults, half of whom complained of a 'delayed sleep schedule' and felt more awake in the late evening.  The researcher found that the group with the delayed sleep schedule had an increased sensitivity to blue light, and more melatonin was suppressed due to the light.

An Oct. 2018 study of teens/young adults looked at the light sensitivity of patients diagnosed with 'Delayed sleep-wake phase disorder' (DSWPD). Researchers compared the circadian phase shifting response to 150 lux of light, which similar to a normal indoor room with the lights on a night. Those with the DSWPD diagnoses had a 31% greater phase delay shift than the control group. They were, simply put, more affected by light at night.

So a good portion of our population is more sensitive to light at night. Blue light suppresses melatonin for everyone, but for some people, it is suppressed more than for others.

You may be mentally arguing that you are genetically wired to stay up late regardless of light, and that may be true. There are several genetic mutations that cause DSPD, but these mutations are somewhat rare. For example, one mutation in the clock gene CRY1 that causes DSPD is found in about 3 out of 1000 people.

What is the solution?
Again, let's take a look at some research.  

A study of 15 - 17-year-olds tested using blue blocking glasses at night for one week during the evening followed by a one night lab test.  The tests looked at melatonin levels, sleepiness, and an overnight polysomnography.  The results showed that wearing blue-blocking glasses in the evening increased the production of melatonin and increased sleepiness at bedtime.

My proposed solution:

1) Education: Teens and young adults are perfectly capable of understanding the science of how blue light at night shuts off melatonin. Let's stop nagging at them to put away their phones at night and give them the factual, scientific reasons for what is going on in their body.

2) Blue-blocking glasses: Teens that choose to use electronics or bright overhead lights at night can also choose to wear blue blocking glasses.

3) Apps and reminders: Use technology to shut off the tech at night. There are many built in apps and ways to remind yourself to shut off the phone / computer an hour or two before bedtime. Humans survived for many millennia  without watching TV or texting friends for three hours at night.

If you are thinking that it would just be simpler to give in and change the school day to run from 10:30 - 5pm, you may be right that it is easier. But the long-term, chronic effects of light at night include obesity, diabetes, cancer, heart disease, and Alzheimer's. Blocking out light at night - and raising endogenous melatonin levels - has long term protective effects against so many chronic diseases.

What can you do?

Share this! Tell someone about it. Get your own teens some blue blocking glasses – and model the behavior for them.