Siesta

A siesta (Spanish pronunciation: [ˈsjesta]) is a short nap taken in the early afternoon, often after the midday meal. Such a period of sleep is a common tradition in some countries, particularly those where the weather is warm. The word siesta is Spanish, from the Latin hora sexta – "the sixth hour" (counting from dawn, therefore noon, hence "midday rest").

The siesta is the traditional daytime sleep of Spain, and through Spanish influence, of many Latin American countries.

Factors explaining the geographical distribution are mainly high temperatures and heavy to very heavy intake of food at the midday meal. Combined, these two factors contribute to the feeling of post-lunch drowsiness. Afternoon sleep is also a common habit in Albania, Bangladesh, Bosnia and Herzegovina, China, Croatia, Cyprus, Greece, India, Iran, Italy (southern), Macedonia, Malta, Montenegro, North Africa, Pakistan, the Philippines, Serbia, Slovenia, Taiwan and Vietnam.

In these countries, the heat can be unbearable in the early afternoon, making a midday break at home ideal. In many areas with this habit, it is common to have the largest meal of the day in the very early afternoon, as is practical and common in farming.

Protection from the sun

A siesta takes place when the sun is at its highest point, this is when the sun's ultraviolet radiation is at its peak at midday. Prolonged exposure to ultraviolet radiation may result in sunburn, especially if one has fair skin. Recurring overexposure to ultraviolet radiation can cause some forms of skin cancer.

The sun's infrared radiation causes high air temperatures from the midday onwards, the highest temperatures taking place in the early afternoon. High temperatures can cause fatigue or in a more serious case heat exhaustion or hyperthermia (sunstroke).

http://en.wikipedia.org/wiki/Siesta