Delegates rest during a break of the plenary session at the U.N. Climate Change Conference. Image: REUTERS/Enrique Castro-Mendivil
Boys who get less “slow-wave” sleep during adolescence have a significantly higher chance of developing insulin resistance as they get older—and are at greater risk for developing type 2 diabetes, increased visceral fat, and impaired attention.
Slow-wave sleep (SWS) is an important stage of sleep that is involved in memory consolidation and recovery after sleep deprivation, and is also associated with reduced cortisol and inflammation. While prior research has shown that SWS declines as a person gets older, there is little research looking at possible physical or neurocognitive consequences of the loss of this type of sleep.
“On a night following sleep deprivation, we’ll have significantly more slow-wave sleep to compensate for the loss,” says Jordan Gaines, a doctoral candidate in neuroscience at the Penn State College of Medicine. “We also know that we lose slow-wave sleep most rapidly during early adolescence. Given the restorative role of slow-wave sleep, we weren’t surprised to find that metabolic and cognitive processes were affected during this developmental period.”
Gaines analyzed results collected through the Penn State Child Cohort in order to study longterm effects of SWS loss from childhood to adolescence. The cohort included 700 children from the general central Pennsylvania population, ages 5 to 12. Eight years later, 421 participants were followed up during adolescence—53.9 percent were male.
Participants stayed overnight both at the beginning of the study and at the follow-up, and had their sleep monitored for nine hours. At the follow-up appointment, participants’ body fat and insulin resistance were measured, and they also underwent neurocognitive testing.
For boys, a greater loss of SWS between childhood and adolescence was significantly associated with insulin resistance, and this loss was marginally associated with increased belly fat and impaired attention. However, Gaines did not find any associations between SWS and insulin resistance, physical health, or brain function in girls.
Importantly, the participants’ sleep duration did not decline significantly with age, suggesting that the effects observed were due to a loss of this “deeper” stage of sleep.
The findings were presented at the annual meeting of the American Association for the Advancement of Science.
“More longitudinal studies are needed to replicate these findings, especially in other age groups,” Gaines says. “Studies looking at the effects of experimentally enhanced slow-wave sleep are also necessary.
“In the meantime, we can use these findings as a springboard for future work on the sleep-health connection. The best thing we can do for ourselves today is keep a consistent sleep schedule, so as not to deprive ourselves of any more slow-wave sleep than we’re already naturally losing with age.”
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The views expressed in this article are those of the author alone and not the World Economic Forum.