Why does the practice of the siesta vary across human cultures? One explanation is that it is a form of energy conservation in environments with high temperatures and/or agricultural labor. Disease palliation and prevention represents another area where the siesta might be beneficial. A preliminary study used the Human Relations Area Files (HRAF) to examine the characteristics associated with siesta occurrence. Siestas were not statistically associated with high temperatures or agricultural labor (p>.05). They were, however, statistically associated with the occurrence (...) of malaria (p<.05) and marginally associated with parasitic and chronic infectious disease. Preliminary results suggest that siestas could be adaptive in environments with chronic infectious disease. (shrink)