In 1952, when medical student William Dement started measuring brain waves and eye movements of slumbering volunteers at the University of Chicago, the world still held two deep-seated assumptions about sleep: It was a passive state — merely the absence of wakefulness — and if you had trouble sleeping, the cause was probably worry.
“We’ve learned that it’s more complicated,” says Dement, now 87, who later founded the world’s first sleep disorders clinic at Stanford University in 1970. He still teaches a class there.
Researchers have since identified up to 88 distinct sleep disorders. They range from REM sleep behavior disorder — a dangerous condition in which people physically act out their dreams — to fatal familial insomnia, a rare neurodegenerative disease in which patients die from lack of sleep.
Psychological factors clearly play a role in some disorders, but recent studies reveal other culprits. Nighttime exposure to glowing e-screens and LED lights can swiftly switch off production of sleep-inducing melatonin and throw off our circadian rhythm, or internal clock. Obstructive sleep apnea — a skyrocketing condition in which the airway collapses, choking off breath and prompting periodic awakenings — has been linked not just to excess weight but also to genetic factors such as a small jaw, recessed chin or Asian background.
