case-control study of a Greek population found that those who took a nap were at a lower risk of developing coronary heart disease than those who did not.
The study appeared in 1988, and it set the tone for much of the ensuing research on napping. Later, a large cohort study, also of a Greek population, confirmed the findings.
It suggested that those who napped regularly had a 37% lower risk of death from coronary heart disease than those who did not nap.However, studies in other parts of the world — such as Costa Rica, United States, Germany, and Japan — all found higher risks of cardiovascular disease and mortality.