Most of us over 40 - OK, 50 - have some trouble sleeping through the night.

And then, perhaps, you will listen to the night, and hear my song when I am silent.

"Because of these impacts, we'd like to know what happens to these nitrogen oxides in nighttime air, where do they go, what do they do, " Thornton said.

People with this problem experience sudden, involuntary leg movements during the night, such as kicking or jerking.

Note: I have divided these into morning, day and night although some could obviously be under different headings.