In the meantime, airline passengers must still practice their conversation (or napping) skills during takeoff and landing.

ENGADGET: Editorial: Devices on planes -- either enforce the rules or change them

The only people who shouldn't be napping are those losing sleep from insomnia or depression.

CNN: Sleep tips for the road-weary

The theory behind outdoor napping is that children exposed to fresh air, whether in summer or the depths of winter, are less likely to catch coughs and colds - and that spending a whole day in one room with 30 other children does them no good at all.

BBC: The babies who nap in sub-zero temperatures