When I seemed to be irritable or sad my father would quote the learned Dr. Knight and then say 'Just go to sleep.' Like all smart aleck kids I thought the advice was silly. But as I've grown older I've realized just how smart Knight was.
In fact I am quite snappy and irritable and I don't know if I'd like to make myself worse in that respect.
I live in Los Angeles which is the second most polluted city in the world and I wake up in the morning to dirt all over my window.