London - If your baby is giving you sleepless nights, science may have the answer – "tummy time".
A study found babies who are more active sleep more and the way for them to get exercise is to spend time on their fronts.
Babies have to use more muscles while on their fronts – to lift their heads, arms and legs - than when they are on their backs.
The Michigan State University researchers analysed 22 healthy six-month-olds and monitored their sleep and activity level.
Janet Hauck, who led the study, said: "Babies who slept less overall in the 24 hours and had the least amount of nighttime sleep had more overnight feedings and were significantly less active during the day."
She added there was no evidence tummy time directly affects sleep but it increases physical activity and promotes healthy weight gain. The study was published in the journal Infant Behavior and Development.