Funktsionaalne kiud – tekid ja padjad

We spend about one-third of our lifetime sleeping. In many societies it was for long thought that, when one was sleeping, the soul left the body in a spirit of adventure and its return to the body resulted in the awakening. From ancient times until the present, poets and thinkers have treasured sleep as a 'Gift of the Gods'. There is little more that can be said on the subject of sleep than the elderly Roman emperor Hadrian (76-136 AD) wrote to a friend: "Of all the pleasures that increasingly elude me, sleep is for me one of the most valuable ...What I find most fascinating is the fact that each night anew naked, lonely and unarmed one dares the unavoidable leap into the ocean depths, where all is changed, the colours, shapes and rhythm of breathing ...". At the onset of the era of technology and the natural sciences, sleep was seen more as a necessary evil to build up strength for the next day. For a long time sleep was seen solely as a passive state. The sleep environment as provided by our present-day bed coverings has only been known since the 18th. century.