Even though the average teen needs eight to ten hours of sleep per night, most fall woefully short of that crucial number. To help teens get more sleep, scientists have proposed pushing back school start times or telling teens to stay away from screens before bed. Failing that, exposing them to some strange flashing lights at night could be a strangely effective strategy, going by a recent trial.

According to the results of an experiment conducted by scientists at the Stanford Center for Sleep Sciences and Medicine, teenagers who are exposed to both cognitive behavioral therapy and two hours of flashing lights at night slept for 43 more minutes on average. Lead study author Jamie Zeitzer, Ph.D. tells Inverse that this trial is the first of its kind to demonstrate that brief flashes of light, called flash therapy, really can help teens adjust their circadian rhythms, a cycle of hormone release that governs when they feel tired.

These results, published Wednesday in JAMA Network Open suggest that flashing light treatments can help teens shift their circadian rhythms forward, which helps them achieve two things: they can go to sleep earlier, and sleep a bit more as a result.

Teens who received cognitive behavioral therapy and "flash therapy" were able to go to sleep 27.5 minutes earlier, and sleep for 43.3 minutes more per night. Marina Teneva, Unsplash

To some extent, circadian rhythms are genetically linked. There are about 351 genes that affect whether someone is a morning lark or a night owl. Night owls tend to feel tired later in the evening and sleep later into the morning, whereas early birds experience the opposite.

There is other research which suggests our circadian rhythms aren’t totally set in stone. Exercising at certain times advances the circadian rhythm, which can make you feel tired earlier in the evening, and ready to wake up earlier in the morning. Meanwhile, exposure to natural light in the morning and eating upon waking up have shown potential to help night owls shift their rhythms forward by about two hours.

Regardless of whether one grows up to be a morning lark or a night owl, most teenagers go through a night owl phase. Teens experience a “sleep phase delay” that makes it harder to fall asleep before about 11 pm. The idea behind this therapy is that that if you can realign this phase, it might be easier to get up for a 7:30 am class.

Here, Zeitzer and his team split 102 high schoolers into two groups. One group slept with a flashing “beacon” light for three milliseconds every 20 minutes during the last two hours of sleep, and the other group got a smaller dose of light. This smaller dose was only three total flashes — theoretically not enough to trigger a circadian shift.

These flashes weren’t disruptive to all the teens — but Zeitzer adds that they did have to reduce the amount of time the lights flashed from three to two hours to make them less annoying, so they’re still being workshopped. In the future, he adds that they may try to back off on the flashes even more. Even so, it’s not a technique intended for light sleepers.

“There are some people who are very sensitive to light during sleep and this would be too disruptive for them,” Zeitzer says.

Importantly, on its own, the flash therapy didn’t affect sleep, but when it was combined with a cognitive behavioral therapy session once per week for three weeks, it did show significant effects on bedtimes and sleep times. In those sessions, teens talked about how circadian rhythms work, how sleep impacts weight, grades, and athletic performance. They also discussed scheduling weekend activities that would force teens to get up a little bit earlier on their off days.

On average, teens who received light therapy and CBT went to sleep 27.5 minutes earlier and slept for 43.3 more minutes. Teens who only got the CBT with no light treatments didn’t increase their sleep duration and were seven times less likely to comply with the earlier bedtimes suggested by their therapists

"In the light plus CBT group, circadian timing was likely moved earlier."

Taken together, these results point to the power of therapy and the light treatment together. Whereas the therapy gave teens reasons to think carefully about sleep, the light treatment tackles the biological angle, which makes it easier to follow their therapists’ advice and go to sleep earlier.

Overall, these trials are a demonstration of a simple way for teens to readjust their circadian rhythms to align more closely to a school or work schedule. Though right now, the lights that Zeitzer and his team used aren’t commercially available.

At this point, a circadian nightlight may be on the horizon, and once it arrives, and if it’s used correctly it may actually be the tool that night owls have been waiting for.

Partial Abstract:

Design, Setting and Participants: This double-blind, placebo-controlled, randomized clinical trial, conducted between November 1, 2013, and May 31, 2016, among 102 adolescents enrolled fulltime in grades 9 to 12, who expressed difficulty going to bed earlier and waking up early enough, was composed of 2 phases. In phase 1, participants were assigned to receive either 3 weeks of light or sham therapy and were asked to try to go to sleep earlier. In phase 2, participants received 4 brief CBT sessions in addition to a modified light or sham therapy. All analyses were performed on an intent to-treat basis.

Results: Among the 102 participants (54 female [52.9%]; mean [SD] age, 15.6 [1.1] years), 72 were enrolled in phase 1 and 30 were enrolled in phase 2. Mixed-effects models revealed that light therapy alone was inadequate in changing the timing of sleep. However, compared with sham therapy plus CBT alone, light therapy plus CBT significantly moved sleep onset a mean (SD) of 50.1 (27.5) minutes earlier and increased nightly total sleep time by a mean (SD) of 43.3 (35.0) minutes. Light therapy plus CBT also resulted in a 7-fold greater increase in bedtime compliance than that observed among participants receiving sham plus CBT (mean [SD], 2.21 [3.91] vs 0.29 [0.76]), as well as a mean 0.55- point increase in subjective evening sleepiness as compared with a mean 0.48-point decrease in participants receiving sham plus CBT as measured on a 7-point sleepiness scale.