Rise and Shine Early birds may have an edge over night owls at work and school -- not just in the morning, when their bodies' internal clocks help them get on task earlier, but through midday. That's according to a study in the journal Chronobiology International that showed morning people are more likely to maintain regular schedules, sleep well and resist depression. Ask them to work late, however, and they may not do as well.

The Study Researchers from the University of Pittsburgh analyzed the sleep-wake habits and activity patterns of 100 healthy adults (25 of whose test responses categorized them as morning types, 25 as evening types and 50 as in the middle). All participants kept two weeks of entries in a "social rhythm metric" diary to measure the regularity of lifestyle activities and completed a questionnaire whose score rated them for "morningness" or "eveningness." As morningness decreased, so did lifestyle regularity -- which is associated with better sleep and more resistance to some kinds of depression.

Change of Pace The study is significant, said lead author Timothy H. Monk, professor of psychiatry at the University of Pittsburgh School of Medicine, because it shows a health impact for behavioral rhythms that most people can control.

Monk said 80 percent of people can switch relatively easily to morningness, by gradually increasing exposure to morning light over several days. Another option is to slowly force oneself onto a different schedule.

But those on the ends of the spectrum -- people who get up at 5, clear their desks by noon and go to bed at 9; or those who rise at 11, work till 9 and go to bed at 2 -- may find switching tougher or impossible, said Monk, who has studied circadian rhythms for 30 years.

-- Suz Redfearn