Does your body know what time it is? Specialized area of brain tied to neurons in the back of eyes which sense light and dark This area of the brain releases melatonin Not clear that taking melatonin helps sighted people to adjust their sleep schedule

Plants, insects, humans and other animals have “circadian rhythms” These are cycles that follow along with the earth’s daily rotation Most people, when isolated from cues, settle into a schedule of about 24 hours One woman who didn’t, in an isolation study, misjudged the amount of time she had been isolated

Lack of sleep can be dangerous! Jet lag: energy level, but also mental skills, and coordination What does this mean for third-shift workers? Genetically, we range from “early birds” to “night owls” When are you most alert? What are you usually doing at that time?

When is the last time you were in a bad mood? A good mood? Write down when it was What was happening that makes you call this a “bad mood”? What was happening that makes you call this a “good mood”?

SAD (Seasonal Affective Disorder) Is it the light or is it Christmas, snow, darkness, and finals? Clinicians estimate as high as 20% Survey data (1998) found.4 percent lifetime prevalence (very small!!!!) Why might we like the idea of SAD?

PMS: 5% Where do you always find your keys? –Journal data vs retrospective data –Men’s journals vs women’s journals Principal of falsifiability: What are the “symptoms” of PMS? –Physical vs emotional symptoms Why might women in our culture like the idea of PMS? Men?

Research conclusions about “PMS” No gender differences in mood No relation between stage of menstrual cycle and emotional symptoms No consistent “PMS” pattern across menstrual cycles No connection between “PMS” and behavior chapter 5