Academic journal

Why your sleep is affected by electric lights

  • A new report reveals that electric light impacts the circadian rhythm in people and can disrupt sleep.
  • Experts explain how people need to be exposed to bright light during the day and evening to help support healthy body rhythms, restful sleep and daytime alertness.
  • Researchers say light affects our daily patterns of sleep and alertness through a specialized cell in the eye using a light-sensitive protein called melanopsin.

A new study published in the journal PLOS Biology indicates that the light humans experience in everyday life strongly influences bodily rhythms, with 24-hour access to electric lights combined with reduced exposure to natural sunlight resulting in sleep disturbances.

According to the study, the combination has a negative impact on human health, well-being and productivity.

Research also recommends how people should be exposed to bright light during the day and evening to help support healthy body rhythms, restful sleep, and daytime alertness.

An international team of scientists led by Timothy Brown, PhD, from the University of Manchester in the UK, and Kenneth Wright, PhD, from the University of Colorado at Boulder, have put together what they say is one of the first evidence-based consensus recommendations for healthy exposure to light in the day, evening and night.

“These recommendations provide the first scientific, quantitative, consensus guidance for appropriate daily patterns of light exposure to support healthy body rhythms, nighttime sleep, and daytime alertness,” Brown said in a statement. “It now provides a clear framework to illuminate the way we light any interior space, ranging from workplaces, educational establishments and healthcare facilities to our own homes.”

The guidelines will be intended to help the lighting and electronics industries design healthier environments and improve the way we light homes, workplaces and public buildings.

Researchers say light affects our daily patterns of sleep and alertness through a specialized cell in the eye using a light-sensitive protein called melanopsin, which is different from the proteins in the rods and cones of the eye. eyes that support vision (on which traditional methods of measuring “brightness” are based).

Melanopsin is most sensitive to light residing in a specific part of the visual spectrum (blue-cyan light). The team developed a new light measurement standard tailored to this unique property called melanopic equivalent daylight illuminance.

The researchers analyzed data from a series of laboratory and field studies, which they say proved that the new measurement approach can reliably predict the effects of light on human physiology and rhythms. bodily.

In doing so, it could allow the team to come up with broadly applicable and meaningful recommendations for how we should use – and not use – light in our daily lives.

The researchers say their next step will be to incorporate recommendations into formal lighting guidelines, which currently focus on visual requirements rather than the effects of light on health and well-being.

They expect increasing sophistication of LED lighting technology and the availability of low-cost light sensors to increase the ease with which people can optimize their personal exposure to light to better support their own bodily rhythms. .

A study published in the journal PNAS from the Center for Circadian and Sleep Medicine at Northwestern University Feinberg School of Medicine focuses on the negative effects of light on sleep and human health.

Researchers have found that sleeping even a single night with dim lighting, such as a TV without sound, increased heart rate and blood sugar levels in healthy young people.

The dim light entered the eyelids and disturbed sleep despite the subjects being asleep with their eyes closed.

The study pointed out that heart rate typically drops at night, slowing as the brain repairs and rejuvenates the body. Numerous studies have shown that an elevated heart rate at night can be a risk factor for future heart disease and premature death.

“The results of this study demonstrate that a single night of exposure to moderate ambient lighting during sleep can impair glycemic and cardiovascular regulation, which are risk factors for heart disease, diabetes and metabolic syndrome,” said said the author of the study and the head of the school. sleep medicine, Phyllis Zee, MD, PhD, told Northwestern Now. “It’s important for people to avoid or minimize the amount of light exposure during sleep.”

The Northwestern team recommended not turning on lights while sleeping. If you need to have a light on (for example, for security reasons), make it a dim light closer to the ground.

They also said that the color of the light is important.

Amber or red-orange light is less stimulating to the brain. Do not use white or blue light and keep the light away from the sleeping person.

They also recommend blackout blinds or eye masks for people who can’t control outside light, and you need to move your bed so outside light doesn’t shine on your face.