• The Ancient Greeks believed in Hypnos, a minor god who is the personification of sleep. The twin brother of death (Thanatos) and the son of Night, he was considered a friend of mortals who was a healer of the body and mind.
• Alcmaeon, a Greek physician from the sixth century B.C., proposed the first documented theory of sleep. He theorized that sleep was a loss of consciousness when blood drained from vessels on the surface of the body.
• Around 350 B.C. Aristotle wrote On Sleep and Sleeplessness. He believed that sleep was the result of vapors which rose from the stomach to the heart during digestion.
• The sleeping pattern of peasants in medieval Europe was fairly unique and is referred to now as segmented sleep. One night’s sleep was divided by a period of semi-conscious wakefulness (the two segments were called first sleep and second sleep) during which time people often prayed or would interpret dreams that were more vivid between sleeps then in the morning.
• Shakespeare often wrote about sleep, dreams, and nightmares. The Elizabethans thought that sleep was the opposite of being awake and often compared it to death.
  
  O sleep! O gentle sleep! Nature’s soft nurse. (Henry IV)
  
  
  

• In 1749, David Hartley published his theory of the Doctrine of Vibrations which states that we are made up of moving particles that must eventually come to rest. Sleep is necessary, but not positive, and oversleeping was considered a sign of sloth and low intelligence.
• Robert MacNish wrote the influential The Philosophy of Sleep in 1830 and claimed that sleep “is the intermediate state between wakefulness and death” and, further, that “sleep is temporary metaphysical death.”
• Narcolepsy was first identified as a chronic neurological condition in 1880 by Jean-Baptiste Edouard Gelineau who observed patients who fell asleep uncontrollably at strange times during the day.
• The first sleeping pill, barbital, appeared on the market in 1903 and was popular with insomniacs and people plagued with anxiety.
• n the beginning of the twentieth century, French scientist Claparède proposed that sleep is a reaction de disinterest, or a loss of interest in the external world.
• Leading sleep researcher Nathaniel Kleitman opened the world’s first sleep laboratory at the University of Chicago in 1925. His book, Sleep and Wakefulness, was published in 1939.
• Hans Berger documented the first recording of electrical activity along the scalp (EEGs) in 1929, marking a turning point in sleep research.
  
  
  

•  The five stages of sleep were identified by Alfred Loomis, E. Newton Harvey, and Garret Hobart in 1937.
• Eugene Aserinsky, an advisee of Kleitman, discovered REM sleep in 1953, after observing the eye movements in his son, who he watched in the sleep lab.
• Another of Kleitman’s student’s, William C. Dement, established that sleep is cyclical in 1954.
• Stanford University opened the first sleep research center in 1970.
• There are currently at least four commonly accepted theories of sleep: adaptive (sleep is a survival function, developed to keep animals safe during the night when they are most vulnerable), energy conservation (sleep reduces our energy demand, especially when it is least practical to get food), restorative (sleep is an opportunity for our body to be repaired and rejuvenated), and brain plasticity (sleep plays a critical role in brain development).

 

Sources:

• Discovery Healthy
  
• Harvard Medical School Division of Sleep
  Medicine: Healthy Sleep
• Interactive Timeline