"Stage 1 is light sleep where you drift in and out of sleep and can be awakened easily. In this stage, the eyes move slowly and muscle activity slows. During this stage, many people experience sudden muscle contractions preceded by a sensation of falling.In Stage 2, eye movement stops and brain waves become slower with only an occasional burst of rapid brain waves. When a person enters Stage 3, extremely slow brain waves called delta waves are interspersed with smaller, faster waves. In Stage 4, the brain produces delta waves almost exclusively. Stages 3 and 4 are referred to as Deep Sleep or delta sleep, and it is very difficult to wake someone from them. "
stages of sleep.
1. Wolfgang Tillmans Freischwimmer 20, 2003, inkjet print
2. Christopher Wool Untitled, 2008 Silkscreen on paper.
(via tonight's auctions lots at philips de pury! go here)