Psychology
A grad student wired his own son to a machine and discovered REM sleep
In 1953, Eugene Aserinsky attached electrodes to his 8-year-old son and noticed the boy's eyes darting beneath closed lids at regular intervals through the night. He and his supervisor Nathaniel Kleitman traced the eye movements to vivid dreaming, revealing that sleep cycles through active, dream-rich stages rather than staying uniform all night. The finding launched modern sleep science almost overnight.