4 p.m.

You’re more likely to whistle while you window wash (and not kick over the bucket) if you do it in the late afternoon. That’s when hand-eye coordination is at its peak and mood levels are high, says Michael Smolensky, a professor of environmental physiology at the University of Texas School of Public Health at Houston and author of The Body Clock Guide to Better Health (Owl Books, $11, www.amazon.com). If anyone in the house has allergies or asthma, avoid insomnia-hour and morning cleaning sprees (nasal-allergy symptoms are most severe between 6 a.m. and noon, asthma attacks more likely between midnight and 6 a.m.), and finish well before that person walks in the door. “It takes about an hour for allergens and dust to settle after you clean,” says Martha White, M.D., director of research at the Institute for Asthma and Allergy, in Wheaton, Maryland.