"We were very surprised to find how little preschool aged children actually sleep at night, which we could measure with our activity monitors. Children in our sample slept only about 8.7 hours at night and less than 9.5 hours per 24 hours when naps were included. This contrasts with the 12 to 15 hours usually recommended for children this age," says lead author Christine Acebo, PhD, of the Bradley Hospital Sleep and Chronobiology Research Laboratory.
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. Several studies in adults also link lack of sleep to neuroendocrine abnormalities that may lead to overeating and obesity.
"We are concerned that the problem of too little sleep extends even to the youngest members of families, though we do not know if this puts them at risk for problems down the line," says Acebo.
The research paper, published in the December issue of the journal Sleep, corroborates the results of a recent survey of parents, funded by the National Sleep Foundation (NSF) and Pampers Baby-Dry, showing that many children from newborn to age four do not get the minimum 12 to 15 hours of sleep per day recommended by the NSF and pediatric sleep experts.
Acebo and colleagues studied 169 children between 1 and 5 years old, once a week in their homes. The children wore activity monitors on their ankles or wrists to record their sleep, and mothers also chronicled their children's sleep habits in detailed diaries.
"We wanted to study sleep in preschool aged children because most of the research in this area is more than 25 years old -- this is one of the first studies to describe sleep patterns in this age group with objective measures in recent years," explains Acebo.
The authors also found an interesting difference between families of differing socioeconomic status (SES).
"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.
In addition, the researchers found that the children in the study awoke more often during the night than is usually described in the scientific literature, but which is consistent with concerns that many parents bring to their pediatricians.
Finally, they report that 82 percent of children older than 18 months were not taking naps on some or all days.
Acebo says that she was surprised to find that kids are sleeping less than the recommendations that have been in place for the past 50 years.
"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.
The results of this study are important because they indicate that all members of American families may be getting insufficient sleep in our fast paced, 24-hour society, Acebo and colleagues say. Their results also reveal that more data is needed to determine how much sleep small children really need and the effects of insufficient sleep on later development
Founded in 1931, Bradley Hospital (www.bradleyhospital.org) was the nation's first psychiatric hospital operating exclusively for children. Today, it remains a premier medical institution devoted to the research and treatment of childhood psychiatric illnesses. Bradley Hospital, located in Providence, RI, is a teaching hospital for Brown Medical School and ranks in the top third of private hospitals receiving funding from the National Institutes of Health. Its research arm, the Bradley Hasbro Children's Research Center (BHCRC), brings together leading researchers in such topics as: autism, colic, childhood sleep patterns, HIV prevention, infant development, obesity, eating disorders, depression, obsessive-compulsive disorder (OCD) and juvenile firesetting. Bradley Hospital is a member of the Lifespan health system.