The Harvard Medical School Guide to A Good Night's Sleep, by Lawrence J. Epstein (TPB, 2007, $2.50)
I was a night worker for 17 years, and loved it, most of the time. The winter was the best part of my year because when it is dark, it is easier to sleep. For me, the sun was the enemy. Now that I am retired, I am still up at night. So, per chapter 3 of this book, I am neither standard, nor a lark, just an owl. Well, I already knew that.
I recommend the chapter on sleep myths. I also recommend the chapter on snoring and sleep apnea. You may not know about sleep apnea, but it can still kill you. Many people don't even know they have it. Either you think it is just snoring, or you sleep alone and don't even know you snore. I stayed over night with a friend after knee surgery, and noticed she would snore, and then would become quiet, on and on during the night. This is sleep apnea, and should be checked out.
Look for this book in the medical section, avail. 2/22