Psychology
Let sleeping teenagers lie

Does your teenager go to bed at unheard of hours and get up in the afternoon? Don't get angry. His biological clock is adapting. You should even encourage him to sleep more. "Everything points to a change in the wake-sleep cycle at puberty, so teenagers should spend more time sleeping than they actually do," explains Luc Laberge, who devoted his doctoral thesis to this question.
His research, carried out at the Université de Montréal Sleep Study Centre at Sacré-Cœur Hospital under the supervision of Dr. Jacques Montplaisir, shows that adolescents sleep less and less as they grow older, and that their need for sleep is not being met.

At 13 years of age, a teenager sleeps an average 9.5 hours a night during the week, which represents one hour less than a ten year-old sleeps. However, the teen will sleep 10 hours a night on weekends. This downward trend continues until the end of adolescence, when the number of hours of sleep during the week will stabilize at around 7 per night in youngsters aged 17 to 19 years.
"In the laboratory, teenagers studied for several consecutive summers nevertheless maintained an average of 9.2 hours of sleep per night," Luc Laberge reports. "Despite the constant sleep duration, they were increasingly tired during the day from one summer to the next. As a result, there appears to be an increase in diurnal somnolence concomitant with the development of puberty."
This phenomenon can also be seen from data he gathered himself: at 13 years, girls sleep close to a half-hour more than boys on weeknights, which tends to confirm the correlation between sleep needs and puberty.

"The National Institutes of Health in the United States consider adolescents to be a risk group for excessive diurnal somnolence, and half of highway accidents attributed to this problem are caused by young people under 25 years of age," he stresses. "We also know that adults who present sleep problems have often begun to be affected during adolescence."

Forcing teenagers to get up earlier by moving the start of classes ahead (as Quebec Education Minister Francois Legault recently proposed) would thus increase the gap between weekday and weekend wakeup times, which would further aggravate the sleep deficit from which many teenagers already suffer, in addition to conflicting with apparent biological rhythms.

Researcher : Luc Laberge
Phone : (418) 541-1234, ext. 2836
Funding : Canadian Institutes of Health Research
Director : Jacques-Yves Montplaisir
Phone : (514) 338-2692