Lack of sleep may not just be a problem for students and adults. A new study shows even preschool children aren’t getting enough Zzz's.

Researchers found children under age 5 got an average of 8.7 hours of sleep at night and 9.5 hours per day including naps, which is far short of the 12 to 15 hours of sleep per day recommended for children in this age group.

“We were very surprised to find how little preschool aged children actually sleep at night," says researcher Christine Acebo, PhD, of the Bradley Hospital Sleep and Chronobiology Research Laboratory, in a news release. "We are concerned that the problem of too little sleep extends even to the youngest members of families."

Although sleeping habits of young children are a major concern for parents, researchers say there is little research on the sleeping patterns of children under 5. Most recent research has focused on the effects of sleep on older children and adults.

"Other studies show that decreased sleep in older children, teenagers, and adults may lead to physical and cognitive problems including decreased physical performance, lower academic performance, and reduced cognitive and other daytime functioning,” says Acebo. “Several studies in adults also link lack of sleep to neuroendocrine abnormalities that may lead to overeating and obesity.”

"I think based on what we know in older children, teens, and adults, it's fair to speculate that insufficient sleep in children would be related to difficulties -- although this is an area that's been little studied for decades," says Acebo.

Parents Often Unaware Kids Aren't Sleeping Enough

Young Children Losing Sleep

In the study, published in the journal Sleep, researchers studied the sleeping habits of 169 children between ages 1 and 5. The children wore activity monitors on their ankles or wrists to record their sleep once a week; their mothers kept detailed diaries of the children’s sleeping patterns.

The results showed that the children slept an average of 8.7 hours per night and about 9.5 hours in a 24-hour period, including naps. In addition, the study showed that 82% of children over 18 months were not taking naps on some or all days.

The National Sleep Foundation and several other children’s health organizations recommend young children in this age group get a total of 12 to 15 hours of sleep a day.

Researchers also found children from families of lower and higher social-economic status (SES) had different sleeping habits.

"Children in families with lower SES spent more time in bed at night with more night waking and more variable bedtimes than those in higher SES families who were in bed for fewer hours, but had more regular schedules," says Acebo.

Late Nights Lead to Problems at School

By Jennifer Warner, reviewed by Louise Chang, MD

SOURCES: Acebo, C. Sleep, November 2005; vol 28. News release, Lifespan.