Light is one of the most powerful signals in our environment—regulating the brain’s internal clock and affecting our sleep patterns, health, mood and more.
Our internal clock, also called circadian rhythm, uses light to keep our bodies in sync with the day-night patterns of the outside world. In the morning, sunlight signals the clock (and, in turn, many processes throughout the body) to “wake up.” As the day progresses to evening and sundown, the withdrawal of light lets us prepare for sleep by allowing for the release of chemicals like melatonin.
It is particularly important that children and teenagers get the sleep they need to feel alert and productive during the school day, as well as for their overall health.
How and When Light Impacts Alertness
Since the brain is set up to respond to the sun, light that mimics sunlight has the greatest potential to affect sleep and behavior. This happens when:
- Light has high illuminance, a measure similar to brightness and measured in a unit called lumens, similar to full natural sunlight, and/or
- Light is blue-rich, containing short wavelengths, measured in a unit called Kelvin (K). Short wavelength light appears as blue-rich, or “cool” light and has a color temperature above 3200-4000K. Longer wavelength light appears as reddish or “warm” and has a color temperature less than 3200.
At home, school and work, it’s possible to harness the power of light to promote healthy sleep, to boost productivity and to improve overall well being. Both natural and artificial light can promote good sleep if they work with the natural patterns of the internal clock.
Not enough sunlight early in the day confuses your body’s internal clock—it’s like a mini form of jet lag. At the same time, reducing exposure to blue-rich light in the evenings allows the internal clock to make us drowsy and sleep well.
Light & School-Aged Children
If students start school without sunlight exposure, it may hinder their ability to fall asleep at night because the internal clock is lacking its most vital signal. Similar challenges may develop for students in classrooms with little or no natural sunlight, or dimly lit classrooms.
Studies of teenagers found that those who wore blue-light filtering glasses in the morning went to bed later and got less sleep overall than those who did not wear blue-light filtering glasses.
The right kind of light in classrooms also has the potential to help students learn. We know that better sleep leads to improved memory, concentration, social interactions and more. But a newer field of research is exploring how light may directly influence learning—not just through better sleep, but by activating the brain during class time.
The questions being investigated in this field include:
- Does certain lighting improve perception, concentration and working speed for students?
- Is certain lighting better for social interaction and collaborative work?
- What is the optimal design for school buildings and classrooms to take advantage of natural light and views of green spaces?
One idea being tested is the use of “dynamic lighting”—lighting with different settings that can be changed by the teacher throughout the day depending on the task students are engaged in. This makes sense, given the power of light with respect to the internal clock and behavior. Eventually, we may know which light improves focus and accuracy, and which light promotes communication and cooperation. All will add to this growing field and help us understand and design light in our homes, schools, offices, and beyond that not only better our sleep, but our overall health and wellness.
Practice Sleep-Friendly Light Patterns
Follow these four simple steps to make sure light helps, not hurts, your child or teen’s sleep.
- Get exposure to sunlight or bright, blue-rich white light in the morning
- Reduce exposure to bright and blue-rich light in the evenings, at least two hours before bedtime.
- Turn off close-range electronic devices (which emit blue light) at least one hour before bedtime.
- Keep electronics out of the bedroom, including electronics and accessories like nightlights, chargers and sound machines that have small blue lights.
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