Older Children May Go to Bed Later, Sleep Less, Feel Drowsier
May 31, 2000 -- Parents have long suspected it, and a new study bears it out: Even before they hit their teens, school-age children start going to bed later, sleeping less, and feeling drowsier during the day.
In addition to finding that sleep patterns change as children get older, the study, published in the journal Developmental Psychology, found that children in families with high stress levels are more likely to sleep poorly. The findings are important, experts say, because too little sleep can cause big problems for schoolchildren.
"We're not always aware of them, but sleep disturbances can have adverse effects on learning, attention, and behavior," says study author Avi Sadeh, DSc, senior lecturer and chairman of child psychology at Tel Aviv University in Israel.
Sadeh explored sleep patterns among 140 children in second, fourth, and six grades. Participants wore wrist monitors for five consecutive school nights. They also completed a survey about sleep habits, along with their parents, and kept daily logs on daytime sleepiness.
Sleep measures included the time the child went to sleep, the time of wakening, number of awakenings, and length of motionless sleep. Poor sleep was defined as a period of sleep with more than 10% wakefulness, or waking more than three times per night.
On average, older children went to bed later, slept less overall, and had shorter periods of true sleep than younger children, with sixth graders sleeping an hour less than second graders. The researchers also found that girls had fewer awakenings and more motionless sleep than boys.
Doctors say sports, homework, and the Internet often keep children up. But "in terms of learning and development, sleep is just as important as extracurricular activities," says Gary Montgomery, MD, director of the sleep center at Scottish Rite Children's Hospital and clinical assistant professor of pulmonology at Morehouse School of Medicine, both in Atlanta.
Over time, late bedtimes cause body rhythms to shift. "In a few years, bedtime can get delayed until 3 a.m., causing major disruptions in academic performance and family life," Montgomery says. "So we retrain sleep and wake cycles so that kids get at least eight hours on a regular basis."