We’ll start this episode by talking about clocks, but not the type of clock that ticks away on your wall. Instead, we’ll talk about the biological clocks that tick inside us. Clifford Saper of the Beth Israel Deaconness Medical Center in Boston will explain some of the research on circadian rhythm and will share his theory about the best way to deal with the disruption of the biological clock caused by jet travel. If you’re traveling this holiday season, or anytime in the near future, give a listen. (Begins at 3:14 )

Do you have a tendency to overeat during the holidays? A new study finds that exercise affects the release of two hormones that help regulate appetite, ghrelin and peptide YY. This may help explain why exercise is often, even if only briefly, associated with suppression of appetite. David Stensel of Loughborough University in the United Kingdom will talk about his study, which appears in the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. (Begins at 11:54 )

Total Time: 20:27