For a healthy heart as young adults, teens need regular bedtimes without screens at hand, Stony Brook study finds

Keep those early and predictable bedtimes for your teenagers — and keep the iPhones out of their bedrooms.

That is the finding of a new study by Stony Brook University researchers who determined that following those guidelines will lead to better cardiovascular health when the teenagers become young adults, and perhaps beyond.

"We found that pretty much all of these dimensions of sleep health" including timing, quality and consistency "at age 15 predicted better cardiovascular health at age 22," said Gina Marie Mathew, a senior postdoctoral associate in the Program in Public Health at Stony Brook and a lead author of the study.

The study was notable because most sleep studies focus on middle-aged and older adults, researchers said. This one involved 307 people from around the country who were monitored for sleep patterns at age 15 and again at age 22. Researchers hope to test them again at age 30.

The study's findings were published in JACC: Advances.

Researchers performed the study in part by attaching a device called an actigraph to the wrists of the people being monitored, which recorded their sleep patterns, Mathew told Newsday.

One surprise was that the amount of sleep young people got did not seem to affect the outcome of the testing or necessarily improve their cardio health, Mathew said. She wasn’t sure why but stressed that sufficient sleep — eight to 10 hours a night for adolescents — is still considered important.

One of the researchers' recommendations is that high schools move back start times to about 8:30 a.m. instead of a more typical 7:30 a.m. since adolescents tend to go to bed later at night as part of their natural sleep patterns.

"Our study strengthens the evidence that healthy sleep patterns during adolescence have lasting physical health benefits," said Lauren Hale, a senior author of the research study and a professor in Stony Brook's Department of Family, Population and Preventive Medicine. "Healthy teen sleep can be supported through a mix of individual behaviors such as consistent bedtimes and removing screens from the bedroom, and broader structural changes like a later high school start time, as one example."

One sleep expert said he thought the study was potentially significant, though with a relatively small sample of about 300 people, more and larger studies should be done to confirm the findings.

"I think their findings are very interesting and potentially important," said Dr. Harly Greenberg, chief of Pulmonary, Critical Care and Sleep Medicine at North Shore University Hospital. "Certainly, this needs to be really confirmed in larger cohorts but it does tell us that sleep timing is very important."

He also said the study underscores the importance of circadian rhythms, or the body’s natural 24-hour clock that tells you when to sleep and wake, much of it dictated by light and darkness.

"When our sleep time is out of synchrony with our biologic clock, when you're sleeping either later or earlier than your optimal circadian time to sleep ... that seems to lead to an increased risk of lots of medical problems," he said.

He noted that adolescents tend to go to bed one or two hours later than adults because of their circadian rhythm, but it would still be helpful for them to get to bed as early as possible.

"When they're forced to wake up early to go to school, their sleep is cut off, so they're sleeping less, and they are out of synchrony with their circadian rhythm," he said.