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. Brazil, colonized not by Spain but by Portugal, stands in cultural contrast.
Factors explaining the geographical distribution are mainly high temperatures and heavy to very heavy intake of food at the midday meal. These two factors combined contribute to the feeling of post-lunch drowsiness. Afternoon sleep is also a common habit in Bangladesh, Bosnia & Herzegovina, China, Croatia, Greece, India, Iran, Italy (southern), Macedonia, Malta, Montenegro, North Africa, the Philippines, Serbia, Slovenia, Turkey 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.
The original concept of a siesta seems to have been merely that of a midday break intended to allow people to spend time with their friends and family. It has been suggested that the long length of the modern siesta dates back to the Spanish Civil War, when poverty resulted in many Spaniards working multiple jobs at irregular hours, pushing back meals to later in the afternoon and evening. However, this hypothesis sounds unlikely, considering that the siesta tradition was very common in Latin America and other countries with Hispanic influence, much before the Spanish Civil War.
the 2'nd picture is A painting of a young woman taking a siesta. (The hammock, Gustave Courbet (1844).)
source : WIKIPEDIA