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."
School-age kids need 10 to 12 hours of sleep to restore the energy needed for growth, Montgomery says. "You can tell that kids need more sleep when they struggle to get out of bed, nap after school, and have poor concentration," Montgomery says. "In fact, some kids are just plain irritable."
Fortunately, there are some simple ways to promote good sleep habits. "Move bedtime up slowly, by a half hour a night," Montgomery says. "Then gradually wind down activity and start bedtime rituals an hour beforehand. For younger kids, warm baths, snacks, and stories are often helpful."
These same techniques apply to adolescents. "My daughter got her days and nights mixed up, so now we're trying to reset her internal clock," says Tonia McCoy-White, mother of 15-year-old Fetausha. "Her room is just for sleep now, not doing homework or watching TV. And there's no napping during the day."
Other good "sleep hygiene" techniques, experts say, include exposure to bright light during the day, limiting caffeine intake, darkening the room for sleeping, and a regular bedtime.
The study was supported by the Israel Ministry of Education and by Helene and Woolf Marmot.
- A new study confirms that sleep patterns vary with age. Older kids go to bed later and sleep for shorter periods than younger kids. Also, nighttime wakefulness is linked with family stress.
- School-age kids need 10 to 12 hours of sleep to restore energy needed for growth. Signs of inadequate sleep are struggling to get out of bed, napping after school, poor concentration, and irritability.
- Sleep habits are improved by moving bedtime up a half-hour each night, gradually winding down evening activity, and beginning bedtime rituals an hour beforehand.
- Good sleep hygiene also includes avoiding daytime naps, limiting caffeine intake, darkening the room for sleeping, and having a regular bedtime.