It is more common in children than adults and is more likely to occur if the person is sleep deprived. (mattresshelp.org)
Both the front - and second - row seats are comfortable for long journeys, as is the third row though probably more for children than adults. (thenewswheel.com)
Now their party has grown into a crowded affair, with more children than adults, but it is still just as much fun. (pearltrees.com)