New research is suggesting links between street lights, neon signs and other forms of nighttime outside lighting and sleeplessness and mood disorders among teens.
The study of more than 10,000 American kids aged 13 to 18 couldn't prove cause and effect. However, it found that teens living in areas with high levels of artificial outdoor light at night went to bed about 29 minutes later, on average, and got 11 fewer minutes of sleep, compared to teens in areas with the lowest levels of outdoor nighttime light.
What's more, greater levels of artificial light were also associated with increased risk of a teen developing a mood or anxiety disorder.
Specifically, teens exposed to higher levels of artificial light at night were more likely to meet the diagnostic criteria for bipolar disorder or specific phobia, according to researchers led by Diana Paksarian, a postdoctoral research fellow at the U.S. National Institute of Mental Health (NIMH).
"Environmental light exposure is only one factor in a more complex network of influences on sleep and behavior," stressed study co-author Kathleen Merikangas, senior investigator and chief of the Genetic Epidemiology Research Branch at the NIMH. But she believes it could be "an important target for prevention and interventions in adolescent health."
As the researchers explained in an institute news release, sleep and circadian rhythm disruptions are features of certain mental disorders, including bipolar disorder. So, disrupted sleep might be the link connecting artificial nighttime light exposures and mental health disorders -- something that should be examined in future studies.
The study also found social disparities in exposure to artificial light. Teens in racial/ethnic minority groups, from immigrant families, or from families with lower incomes were more likely to live in areas with high levels of outdoor light at night, the research showed.
Two psychiatric experts who read over the new findings agreed that more research is needed.
While "it remains unclear what the mechanism of action may be," the link between nighttime light and teen mental well-being "merits further investigation," said Dr. Victor Fornari, vice chair of child and adolescent psychiatry at Zucker Hillside Hospital in Glen Oaks, N.Y. "Limiting artificial nighttime light may have a beneficial impact on mood," he theorized.
Brittany LeMonda is senior neuropsychologist at Lenox Hill Hospital in New York City. She called the study "an interesting and timely article, as adolescents continue to face increasing levels of academic and performance stress."
LeMonda said that "sleep is a vital aspect of brain health, physical health, cognitive health, and emotional, and is especially important during our formative adolescent years. We know that many adolescents do not get enough sleep, due to sleep latency, awakenings throughout the night, or early wake up times."
But there are easy solutions at hand, she added.
"The good news is that simple solutions -- such as blackout curtains or using rooms not facing artificial light sources as bedrooms -- could be positive and possibly simple interventions to reduce light, and hopefully improve sleep patterns and health outcomes," LeMonda said.
The study was published online July 8 in JAMA Psychiatry.
The National Sleep Foundation has more on teens and sleep.