April is allegedly the cruelest month, but October and November could give it a run for its money. In the northern hemisphere, the nights are noticeably drawing in, especially now the clocks have gone back, and sunset is an hour earlier. Every day, it gets darker two minutes more prior than it did the day before. And, while there are compensations-- hello moon! Hello, stars! Hello, most of all, Orion the Hunter, back in our northern skies after long months below the horizon-- many of us cannot be consoled. As one of his patients told the US psychiatrist Norman Rosenthal: "I didn't realize how quickly we hemorrhage light." "I love that expression 'the hemorrhaging of light,'" Rosenthal says. According to Rosenthal, who has spent more than 30 years studying the effects of seasonal changes on mood, about one in five Americans suffer some "winter blues." When we speak, it is 8.30 am in his hometown of Bethesda, Maryland, and he is sitting in f