When people have a hard time sleeping, or waking up, or staying awake during the day, often it’s because their natural circadian rhythms have gotten off-kilter. But new technologies — including special masks, glasses, heart sensors and apps — are trying to remedy that.
“Think of [the circadian clock] as the conductor of an orchestra, and all your organs are the different instruments,” says Jamie Zeitzer, a professor of sleep medicine at Stanford University.
Unfortunately, if that internal clock gets shifted, it can set off a cascade of problems, including changes to metabolism and immunity that have been linked to cancer, heart disease and overall fatigue.
And, so, new technologies are working to reset internal clocks the right way, even as smartphones and other gadgets have been rightly blamed for many of our unhappy circadian shifts.
The light that stimulates
In the morning and afternoon, it’s important to take in blue light — the short-wavelength, high-energy light that stimulates the body. The sun is the main blue light generator, but fluorescent lighting and computer and phone screens also emit the high-energy light, and at a much closer distance to the eyes and at all times of day. Sun-generated blue light dissipates and shifts to lower-energy red light toward the end of the day.
Ideally, humans get enough blue light from going outdoors, but on a dark day, especially when you’re stuck indoors, tech could help make up for a blue light gap, says Phyllis Zee, director of Northwestern University’s Center for Circadian and Sleep Medicine.
She recommends circadian lighting systems, in which many smart lights are installed throughout a home. They create a semblance of natural blue light during the day, then shift later on to longer-wavelength lighting that resembles amber sunsets that cue our bodies to prepare for sleep.
“That will allow us to remain more stably entrained to the light-dark cycle,” Zee says.
Because such systems can cost thousands of dollars, however, a more feasible alternative is buying “red-green-blue” smart bulbs, also known as “RGB bulbs,” which produce many colors. The relatively low-cost bulbs can be adjusted by remote control or programmed to change automatically as the hours pass, so they look blue during the day and red at night.
Users should take all technology promises “with a grain of salt,” says Mariana Figueiro, director of Mount Sinai’s Light and Health Research Center in New York. “There is still the need for researchers to validate the results obtained with many of these devices.”
A light recipe for good sleep
Figueiro is studying the use of special eyeglasses by older people. In their late 60s, many people become less sensitive to light, especially short wavelengths; the front of the eye absorbs more of this light, so not as much can get through to the master circadian clock in the brain. The deficit upsets rhythms — sleep cycles, in particular.
In some seniors, such disturbances are associated with cognitive decline and a disconnect between the master clock and the body’s more specific, peripheral clocks.
The glasses Figueiro examined bathe the eyes in blue or green light, the same sort of short wavelength light we take in from the sun in the morning and early afternoon. On cloudy days, the glasses can remind body clocks that it’s time to decrease production of the hormone melatonin, which can trigger daytime drowsiness.
In her study of lighting and people with Parkinson’s disease, “the results have been very good,” Figueiro says. When the glasses were used along with other light technologies, such as special floor lamps, every morning for two hours over a period of one month, the patients took fewer naps during the day, fell asleep more easily at bedtime and slept about 20 minutes longer at night, according to Figueiro’s preliminary data.
Figueiro says the most important nighttime strategy is to turn down lights — whether red or blue. And, she adds, many of us already possess one type of technology for doing this: dimmer switches. Unlike blue light, red light doesn’t suppress melatonin at night, but too much of any bright light can arouse the nervous system to disrupt circadian rhythms.
If you must use a television, phone or computer in the evening, blue-light-blocking glasses can help. Orange-tinted shades work best, Figueiro says. They’re dark enough to filter out enough light while still allowing clear vision.
Downloadable programs such as f.lux and Windows Night Light can also help — they shift computers to a warmer, less stimulating mode at night.
Reset the circadian clock
Zeitzer is a scientific adviser for a sleep mask that flashes light through the eyelids in the wee hours of the morning, just enough to rewind the brain’s clock without waking its wearer until sunrise. Compared with continuous light, flashes may be more effective at penetrating the eyelids to reach the brain, according to a study published last year by Zeitzer and other scientists in the journal Proceedings of the Royal Society B.
Zeitzer tested mask use among about 100 teenagers, a population notorious for circadian struggles. When teens combined wearing the masks with cognitive behavioral therapy, they woke up earlier, got to bed on time and slept an average of 45 minutes longer.
Calendaring sleep at night is essential, says physician Royan Kamyar, who created Owaves, an app that lets people plan their daily schedules according to their circadian rhythms.
Research suggests the digestive system is most effective at absorbing nutrients and medicines at certain times; the Owaves app provides daily pie charts and notifications nudging you to eat in the morning, midday and just before sunset. “There’s merit to eating in a time frame that’s evolutionarily appropriate — between sunrise and sunset,” Kamyar says.
Such apps encourage users to actively manage their circadian calendars, partly because biological clocks for eating and exercise can vary depending on the individual.
Michael Grandner, director of the Sleep and Heath Research Program at the University of Arizona, says the calendar concept is promising in theory, pending studies that prove they help.
“We should plan our sleep opportunities ahead of time to get the amount of sleep we need,” he says. “That also means we should explicitly plan to allow sufficient time for our wind-down routine before going to sleep,” while calendaring time for meals and workouts earlier in the day.
People can adjust their routines as they observe how scheduled activities affect health metrics on their Apple watches, Oura Rings and other monitors.
And in coming years, doctors may be able to directly measure our internal clocks. Zee has studied the possibility of a blood test that could show whether circadian clocks are running too fast or slow. Such tests have been developed but they need more study.
Once physicians have an easy method to monitor the timing of internal clocks, the goal is to prescribe treatments that more precisely support healthy circadian rhythms.
“The technology will soon be available,” Zee says.