Toddlers drop naps when their brains are ready, rather than at a certain age, a study had found, as experts urged parents to let their children sleep.
Napping is known to be vital for brain development and memory processing, but scientists are still unclear about when and why toddlers stop taking naps.
Professor Rebecca Spencer, from the University of Massachusetts, is leading an investigation into why some four or five-year-olds favour a daily nap, while some three-year-olds have stopped.
The findings showed a “relation between nap transitions and underlying memory and brain development”, and were published in the Proceedings of the National Academy of Sciences by Prof Spencer and co-author Tracy Riggins from the University of Maryland.
Prof Spencer added: “When little kids are napping, they consolidate emotional and declarative memories, so then you ask yourself, when this is such an important time of learning, why would they transition out of napping if napping is helping learning? Why not just keep napping?”
The study has been centred on the brain’s hippocampus, which plays a major role in developmental learning and memory processes.
Their previous work has shown a difference in the development of the hippocampus for children who nap and those who have stopped.
When young children have an immature hippocampus, it reaches a limit of memories that can be stored without them being forgotten, triggering the need for sleep, the authors say.
Napping allows these memories to then be processed into the brain’s cortex, freeing up space in the hippocampus for more to be stored when they wake up.
“When the hippocampus is inefficient, it’s like having a small bucket – your bucket is going to fill up faster and overflow, and some memories will spill out and be forgotten”, Prof Spencer said.
“That’s what we think happens with the kids that are still napping. Their hippocampus is less mature, and they need to empty that bucket more frequently.”
When the hippocampus is more developed, children can move away from taking naps because their hippocampus has matured to a point that their “bucket” will not overflow.
The suggestion is that they are able to hold on to memories until the end of the day, when overnight sleep can do its work in moving memories to the brain’s cortex.
Prof Spencer said growing evidence suggests it is important that all young children are given the opportunity to nap.
But she said further studies are now needed to follow children over time.
Forcing children to stop taking naps “could lead to suboptimal learning and memory”, she added.
