VICTOR HOFFSTEIN, M.D., Ph.D., heads the Division of Respirology and the Sleep, Nose, and Sinus Clinic at St. Michael's Hospital in Toronto. He has published over 150 professional articles and is a frequent guest on radio and television. SHIRLEY LINDE, Ph.D., is a medical writer and coauthor of 15 books, including the national bestsellers No More Sleepless Nights (Wiley) and Dr. Atkins' Superenergy Diet.