Taking a siesta is a common practice worldwide, especially in hot tropical regions. In those areas, it appears to be an evolutionary adaptation to the heat of the midday sun, which limits the activities that are possible without expending considerable effort to remain cool.
There is little evidence concerning the influence of a siesta on nocturnal sleep quality. But it seems that subjective perception of nocturnal sleep is undiminished in midday sleepers. There is even evidence that siestas can increase daytime alertness and counteract the effects of sleep deprivation, thus improving daily work performance.
As far as the medical benefits of the siesta go, there are mixed messages. Some studies have linked siestas with an increased risk of myocardial infarction, while others suggest they may protect against coronary artery disease. This discrepancy may result from the fact that in some societies a siesta is part of a sedentary lifestyle, which includes other risk factors like obesity, diabetes and hypertension. In less sedentary societies, the siesta may represent an important stress-coping mechanism that actually provides protection against coronary artery disease.
So if you are somebody who leads an active life and eats healthily, go ahead and take an after-lunch nap. If you’re lucky enough to have time to, that is!