Bright light phase shifts the human melatonin rhythm during the Antarctic winter

first_imgIn most species daily and seasonal changes in the light-dark cycle are the most important synchronisers (zeitgebers) of daily and seasonal rhythms. In humans only bright light (2500 lux) appears to be an effective circadian zeitgeber. Seasonal effects of light on human physiology have not been investigated. We have exploited the low intensity illumination of the Antarctic winter to investigate the effects of bright-or dim-light treatment for an hour in the morning and in the evening (a ‘skeleton’ 12.5-h day) for 6 weeks on the plasma melatonin rhythm, together with mood and a number of behavioural variables. In parallel seasonal changes in melatonin were observed. Melatonin is known to convey daylength information in photoperiodic seasonal breeders through characteristics of its night-time secretion profile. Bright-, but not dim-, light treatment in winter induced a marked phase advance of the melatonin rhythm, similar to that found in the summer, without marked effect on the other variables. Thus at least one human seasonal change appears to be light-dependent.last_img read more

Are presidential primary debates working?

first_imgMark McKinnon wonders if the course of history would have been altered had P.T. Barnum moderated the famed Lincoln-Douglas debate in 1858, implying that today’s political debates are a bit of a circus.In his new research paper, “Gone Rogue: Time to Reform Presidential Primary Debates,” the author asks: Does the current primary debate process best serve voters, the candidates, the parties, the nation – or is there a better way?McKinnon, a political consultant who served as a Fellow at Harvard Kennedy School’s Shorenstein Center on the Press, Politics and Public Policy during the fall of 2011, argues that over the decades debates have proven to matter although at times the formats detract from the substance.“Memorable debate moments have helped shape presidential primary contests,” he writes. However he adds, “From my perspective, both as a one-time insider and now outsider to the process, the debate formats, timing, moderators and questions no longer showcase the candidates’ strengths or encourage dialogue on the substantive issues most important to primary voters. Creating reality-TV conflicts, seeking unrealistic 60- second solutions to unrest in the Middle East and allowing only 30-second sound bite rebuttals may drive better ratings but not a better democratic process.”The author admits that opinions vary about what specific guidelines should be utilized for future presidential primary debates. But McKinnon claims that most of the candidates, campaign managers, party officials, members of the media and voters interviewed agree on some general principles.last_img read more