Reuters: “If teens’ sleep patterns are in conflict with their natural circadian rhythms, then that also has repercussions on cognitive function and emotional regulation as well as potential health consequences,” said Dr. Judith Owens, director of Sleep Medicine at the Children’s National Medical Centre in Washington, DC, who was not involved in the study.
Based on surveys of adolescents across the US in the 1990s, and follow-up surveys as those kids grew into adulthood, researchers at the University of California, Berkeley, analysed why teens were getting too little sleep and what the long-term effects might be. It’s estimated that between 45 per cent and 85 per cent of sixth-to-12th graders sleep less than the recommended nine hours on school nights, according to the report in the Journal of Adolescent Health. And nearly half of students — 44 per cent — report difficulty staying awake during school, the authors write.
Lauren Asarnow and her colleagues used data from the National Longitudinal Study of Adolescent Health, a large ongoing study mandated by Congress. It began by interviewing adolescents in grades seven through 12 in the United States during the 1994-95 school year. The participants have been followed with four ‘waves’ of further interviews so far. The researchers used information from the first two Waves (1994-1995 and 1996) to study the bedtimes of 2,700 teens during the school year and during summer recess. They used information from the third Wave (2001-2002) to look for emotional distress. At Wave I, 23 per cent of the adolescents reported going to bed at 11.15pm or later during the school year and 73 per cent said they usually slept fewer than nine hours per night.
At Wave II, 22 per cent of the adolescents reported going to bed at 1.30am or later during the summer, and 23 per cent said they went to bed after 11.15. Eighty per cent said they usually slept less than 9 hours per night.
Adolescents who had late school year bedtimes in Wave I were more likely to have emotional distress in Wave III. Late school-year bedtimes in Wave II were not linked to emotional distress in Wave III, but late summertime bedtimes were.
Late school year bedtimes in both Waves I and II were also tied to lower grade point averages, though summer bedtimes had no association with lower grades.
While bedtime appears to be important to later distress, the researchers note, they were surprised to see that short total sleep times were not linked to distress or to lower school grades in Wave III. The study also cannot prove that late bedtimes caused distress or problems at school, it only shows an association.
But, the authors write, “these findings underscore the importance of intervention strategies that target bedtimes in an effort to reduce associated functional impairments, and improve academic and emotional outcomes.”
The timing of bedtime is potentially just as important as the amount of time teens sleep because, like everyone else, they have a natural circadian rhythm.
“Adolescents really can’t fall asleep much before eleven and are biologically programmed to wake up about eight,” Owens told Reuters Health.
Owens, a professor of Pediatrics at George Washington University School of Medicine and Health Sciences, said adolescents typically need nine hours of sleep in order to perform at optimal levels. Owens said three areas of the brain develop throughout adolescence and these are also affected by sleep. The prefrontal cortex has control over the so-called executive functions, things like the ability to manage your time and predict the outcomes of your behaviour; the amygdala is involved in emotional control and the striatum is involved in risk- and reward-type behaviours.
“People who are sleep deprived tend to perceive less in the way of negative consequences for taking risk and so they’re more likely to take them,” Owens said.
Owens is concerned that not much is known about the long-term effects of sleep issues, and worries kids may be up for being overweight, or having type II diabetes and having cardiovascular consequences.
© khaleej TimesNov 2013