Lying, standing, face down, on the side: How animals sleep
16:32 18/03/2011 The World Health Organization declared March 18 World Sleep Day. All living beings spend their lives in an alternating pattern of sleep and wakefulness. However, unlike people who are programmed to sleep at night, some animals can sleep during day time, some at night, while others try to stay awake as much as possible: so they are always on alert.