Free Willpower by Roy F. Baumeister

when glucose is low. It stops doing some things and starts doing others. That may help explain why depleted people feel things more intensely than normal: Certain parts of the brain go into high gear just as others taper off.
    As the body uses glucose during self-control, it starts to crave sweet things to eat—which is bad news for people hoping to use their self-control to avoid sweets. When people have more demands for self-control in their daily lives, their hunger for sweets increases. It’s not a simple matter of wanting all food more—they seem to be specifically hungry for sweets. In the lab, students who have just performed a self-control task eat more sweet snacks but not other (salty) snacks. Even just expecting to have to exert self-control seems to make people hungry for sweet foods.
    All these results don’t offer a rationale for providing sugar fixes to anyone, human or canine, outside the laboratory. The body may crave sweets as the quickest way to get energy, but low-sugar, highprotein foods and other nutritious fare work just as well (albeit more slowly). Still, the discovery of the glucose effect does point to some useful techniques for self-control. It also offers a solution to a long-standing human mystery: Why is chocolate so appealing on certain days of the month?

Inner Demons
    Whatever you think of Jennifer Love Hewitt’s acting ability, you have to give her credit for originality when she was cast in a film version of “The Devil and Daniel Webster.” She shared star billing with Anthony Hopkins and Alec Baldwin, which would have been a daunting enough proposition for any young actress, but she also had the challenge of playing the Devil. If your goal, as drama coaches say, is to “inhabit the character,” a demon poses more difficulties than, say, a police officer. You can’t do field research by riding around in a squad car with Satan. But Hewitt came up with an alternative method of role prep.
    “I started paying close attention to myself and how I felt when I had PMS,” she said. “That’s what formed my basis for playing Satan.”
    If that strikes you as a singularly dark view of premenstrual syndrome, you haven’t spent much time at PMSCentral.com and the other Web sites where women swap remedies and stories. They joke that PMS stands for Psychotic Mood Shift, or simply Pass My Shotgun. Or they share genuine PMS stories like this one:
    It ruins a large portion of my life. I have swollen, puffy eyes, I can’t think straight, I make wrong decisions, ugly emotional outbursts, irrational thinking, purchases I have to return, overspending, quit jobs, extremely tired, cranky, crying, extreme emotional sensitivity, body aches all over, nerve pain, blank staring, that “not here” feeling.
    PMS has been blamed for everything from chocolate binges (it also stands for Provide Me with Sweets) to murder. After Marg Helgenberger, a star on the CSI television show, was photographed at an awards dinner with oddly colored hair, she explained: “That shade was known as ‘PMS Pink.’ I was totally PMSing that day. I was crazy! What did I think, I was gonna get away with pink hair on CSI ?” The word crazy was also used by Melanie Griffith in diagnosing the PMS state that drove her to file for divorce and then abruptly change her mind, although her publicist preferred to use more clinical terms, calling it “an impulsive act that occurred during a moment of frustration and anger.” Over and over, women describe being mysteriously overcome by impulses that seem weirdly alien.
    These dark mood swings have also mystified scientists. To evolutionary psychologists, it seems especially counterproductive for a woman in her childbearing years not to get along with the people around her. Isn’t empathy a crucial skill for raising children? Isn’t it useful to maintain good relations with a mate providing child support? Some scientists, noting that a woman reaches this premenstrual phase of the