The babies who nap in sub-zero temperatures

Would you put your baby or toddler outside in the freezing cold for their lunchtime nap? Most Nordic parents wouldn't give it a second thought. For them it's part of their daily routine.

Daytime temperatures this winter in Stockholm have regularly dropped to -5C (23F) but it's still common to see children left outside by their parents for a sleep in the pram.

Wander through the snowy city and you'll see buggies lined up outside coffee shops while parents sip on lattes inside.

And if you are visiting friends and your child needs a nap, you may be offered the garden or balcony instead of a bedroom.

"I think it's good for them to be in the fresh air as soon as possible," says Lisa Mardon, a mother-of-three from Stockholm, who works for a food distribution company.

The youngest, Alfred, is two and she puts him outside in the pram to nap once a day, for an hour and a half. When he was younger he slept outside twice a day.

Many parents also believe their children sleep better and for longer in the open, and one researcher in Finland - outdoor napping is popular in all the Nordic countries - says she has evidence from a survey of parents to back this up.

According to her research, -5C is the best temperature for an outdoor nap - though some parents she spoke to even put their children out at -30C.

But do children who sleep outside end up catching fewer coughs and colds?

Paediatrician Margareta Blennow says reports from the Swedish Environmental protection agency show conflicting results.

There is a Swedish saying that encapsulates this thought - "There is no bad weather, only bad clothing."

Another saying sums up what Swedes are likely to think when toddlers in other countries are kept indoors in sub-zero temperatures: "A little fresh air never hurt anyone."