Toddlers who have problems sleeping are twice as likely to smoke or use alcohol or drugs as teenagers, researchers say.
Early sleep problems could affect teen smoking
The University of Michigan scientists say sleeping badly as an infant does not mean a child will definitely abuse substances as a teenager.
But they say early sleep disruption could be a "marker" for later problems.
Writing in Alcoholism; Clinical and Experimental Research, they say their findings show the importance of ensuring children sleep well.
The relationship between sleep problems and the use and abuse of alcohol in adults is well known, with people using drink to help them sleep, but the researchers say this is the first study to look at the issue in children.
Anxiety and depression
The team followed 257 boys and their parents for ten years.
When the children were aged between three and five, their mothers were asked if they had trouble sleeping, or were overtired during the day.
Between the ages of nine and 11, children's mothers were again asked about attention problems, aggression and signs of anxiety and depression.
Finally, aged 12 to 14, the boys themselves were asked
about drink, drug and smoking habits.
A third of the children were found to have had a sleep problem in early childhood.
Boys with early-childhood sleep problems were more than twice as likely to have started using alcohol by age 14, and to smoke cigarettes occasionally or regularly, and to use illicit drugs compared to boys whose mothers had not cited sleep problems.
Sixty per cent of the boys had one parent with an alcohol problem.
They said the link between sleep problems and substance use remained strong even after other issues such as depression, aggression, attention problems and parental alcoholism were taken into account.
Long-term data on girls are not yet available.
Regular sleep pattern
The researchers say there may be a common biological factor underlying both early sleep problems and addictive behaviour.
But they stress parents should see their finding only as one more reason to focus on healthy sleep habits for their children -- not as a reason to worry.
The researchers say that, as parents and doctors can improve children's sleep habits, the long-term risk of substance misuse could be addressed.
Dr Robert Zucker, who led the research, said: "What's so interesting about this finding is that the effect exists regardless of a number of other factors that previously had been identified as relating to risk for substance use and abuse.
"It appears to indicate some shared neurobiological dysfunction whose details we don't yet know. Further studies will be crucial to our understanding."
Professor Maria Wong, who also worked on the study, added: "Parents should pay attention to their children's complaints about insomnia and overtiredness.
"They should set a regular sleep schedule for their child, ensure they get adequate amounts of sleep, and encourage their children to engage in relaxing, not stimulating, activities before bed."
Neil Stanley, of the British Sleep Society, told BBC News Online: "We know that sleep is very important for children and their growth.
"The more we learn about it, the more we see how important a good night's sleep is for children."
He said the research was another indication that parents should ensure children got the sleep they needed.
"We shouldn't pretend that children can self-regulate. They rarely say 'I need to go to bed'.
"They do have to have the barriers laid down for them.