tl;dr Viewing artificial light at night disrupts sleep. Sleep plays a vital role in health. For better sleep, turn off or put away artificial light-emitting screens and dim overhead lights 1-2 hours before bed.

This is part 2 of a 3-part series on light and the body.

1. Your body on natural light: energy, mood and more

2. Light and sleep: it matters

3. Sun exposure and vitamin D

How does light exposure impact sleep?

“Daily light exposure, including the type of light we see as well as when and how long we’re exposed to it, has a critical effect on sleep.

Light also affects the production of melatonin, an essential sleep-promoting hormone.”

[source]

Either a lack or an excess of light can have significant effects on health and mood.”

[source]

What are the negative effects of artificial light?

“Exposure to light at night strongly suppresses melatonin, which interferes with sleep timing and sleep quality.

What is sleep quality?

Sleep timing, duration, structure (REM & deep sleep), and the number of sleep disturbances.

The research

• Individuals who used an eReader (30–50 lux) during the 4 hours before bedtime experienced increased latency to fall asleep and decreased morning alertness.

• Individuals who slept with a night light of ~40 lux had shallower sleep and increased arousals, as well as markedly decreased brain oscillations during sleep.

Brain oscillations during sleep have been linked to cognition.

• Two large epidemiological studies reported that even light pollution outside the home was sufficient to disrupt sleep.

Artificial light at night can cause serious circadian and physiological disruption.”

[source and source]

What is lux?
Lux is the unit of illuminance.

Why is high quality sleep important?

Sleep plays a vital role in

1. Heart & circulatory system

   Lowering the risk of coronary heart disease, high blood pressure, obesity, stroke

2. Hormone production

3. Metabolism

4. Respiratory and immune systems

   When we sleep, a particular type of immune cell works harder.

5. Thinking & memory

6. Mental health

   Including emotional regulation

[source]

Why We Sleep is a great resource on the health impacts of sleep for children, adolescents and adults.

What’s the recommendation for nighttime screen usage?

“Tucking your devices away for the night an hour or two before bed is a good rule. That includes not just phones but also other devices and electronics. While smartphones are typically the main culprit, even tablets and TVs can contribute to poor sleep.”

[source]

I watch television at night. The distance from my face to the screen is about 9 feet. It seems to be less disruptive than a phone, tablet, or laptop, which are much closer. Turning the TV off an hour before bedtime would be better, but I’m not there yet.

I put my phone down around 8pm. My phone does not enter my bedroom. I put my laptop away before dinner. I want to be on my laptop when my focus and productivity are highest. That’s during the day.

I have bluelight blocking glasses from BlockBlueLight.* They may help.

Try these experiments

• Turn off or put away all screens 2 hours before bed. What time do you naturally fall asleep?

• Notice the difference in your sleep patterns on a ‘no screens night’ and a ‘late screens night.’

Is viewing natural light helpful to sleep?

Yes!

“Natural daylight at high intensities as experienced outside buildings has previously been shown to

1. advance the timing of sleep to earlier hours,

2. affect the duration of sleep, and

3. improve sleep quality.”

[source]

“Sunlight viewed in the late afternoon/evening communicates to the brain’s circadian clock that it is evening and time to begin the process of transitioning to sleep that night.”

[source]

More ways to take action

Try getting outside in the evening or late afternoon for a short walk.

Traveling? Do the same when you arrive in the new timezone to help your circadian clock adjust more quickly.

Notice how you sleep. Notice any other positive effects on your health, including mood and energy.

Combine natural light in the morning and evening with movement and you have the perfecta.

Technology is great. It’s also important we understand how it impacts our health. The tech companies aren’t going to do this for us. Technology is moving at lightning speed. Information about its health consequences is not.

We can do our own research. We can lean on a trusted source to share the research. We can experiment with alternative routines and habits. We can then decide what’s best for our individual health and well-being.

Making a change requires breaking one habit and replacing it with another.

Starting small is better than not starting at all.

Have you tried a ‘no screens at night’ experiment? Let me know how it goes!

Thanks for reading!

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Eat more plants. 🥦 Hydrate.🚰 Move.🤸 Prioritize sleep. 🛌

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