The researchers note no side effects in any of the patients.

But the same seems to be true of happy people, the researchers noted.

But other researchers noted that the study looked at people who already had a problem, not those trying to prevent one.

Few participants were over 10 years old, so it's not clear if the results apply to older children, the researchers note.

The researchers note that numbers of "near miss" events are not available.

If so, the researchers note, the change has happened remarkably fast.

The researchers noted the kids' medical history and exposure to smoke.

Many women have no idea which risk category they belong to, researchers note.

Those minutes, the researchers noted, give the victims time to find a place to sit or lie down.

Religious or spiritual ties may also help, the researchers note.