This factor combined with watching too much of television elevates the risk even further.

The scientists from Harvard Medical School say children who sleep less than 12 hours and who watch two or more hours of television each day have a 16 percent chance of becoming overweight by age 3.

Dr. Elsie Taveras, an assistant professor at Harvard's Department of Ambulatory Care and Prevention says mounting research suggests that decreased sleep time may be more hazardous to our health than first imagined and such hazardous effects are true even for young infants.

Dr. Taveras is the lead author of a long-term study of the effects of diet and other lifestyle factors on maternal and child health called Project Viva.

The researchers identified 915 mother-infant pairs from Project Viva, and recorded infant weight and measurements at a number of personal visits.

The mothers were asked to record how many hours their child slept each day on average at 6 months, 1 year, and 2 years and to report the average number of hours their children watched television on weekdays and weekends.

The research team found that the combination of low levels of sleep and high levels of television viewing appeared to be synergistic and was associated with significantly higher BMI scores and an increased risk of becoming overweight.

Watching too much television viewing is a known risk factor for children becoming overweight, and a similar link has been found between sleep restriction and overweight in older children, adolescents and adults.

Previous research with adults, adolescents and older children has shown that restricting sleep changes hormone levels, which could stimulate hunger and increase weight gain.

However the study's senior author Dr. Matthew Gillman says this the first study to examine the connection in very young children.

Dr. Taveras says the presence of TV, Internet, and video games in the rooms where children sleep means getting enough sleep is becoming more and more difficult for children to achieve.

She suggests parents can improve children's' sleep quality and duration by removing TV from their children's bedrooms.

The study findings provide further evidence that reducing television viewing to promote adequate sleep will prevent and reduce unhealthy childhood weight-gain.

Children who are overweight are later in life more prone to obesity and related conditions, such as hyperlipidemia, hypertension, asthma, and type II diabetes.

The research was supported by funds from the National Institutes of Health, the Harold Amos Medical Faculty Development Program, and the Robert Wood Johnson Foundation.

The research is published in the current issue of Archives of Pediatrics & Adolescent Medicine.