The study, published in the Journal of the American Geriatrics Society, said the results are in contrast to a number of prior studies which have indicated that daily napping improves health.
Study co-author Katie L. Stone of the California Pacific Medical Center Research Institute said that additional studies are needed to explain why napping is linked with increased risk of death.
Four communities consisting of 8,101 Caucasian women age 69 and older were studied over a seven-year period. Women who reported napping daily were 44 percent more likely to die from any cause, 58 percent more likely to die from cardiovascular causes and 59 percent more likely to die from non-cardiovascular, non-cancer causes.
The findings also showed that older women who reported sleeping between 9-10 hours per 24-hour period also had a greater risk of mortality compared to those who slept between 8-9 hours.
The study should not be interpreted to mean that napping causes poor health outcomes, and it is not recommended that older adults avoid napping, Stone said.
"Since excessive sleep suggests that night time sleep is disrupted, interventions to treat sleep disorders and improve sleep quality in older women may reduce mortality risk," Stone said in a statement.