Michael Jackson's profound difficulty sleeping has taken center stage in the controversy surrounding his death, with expert testimony at his wrongful death trial suggesting the pop singer went a full 60 days without "real" sleep.
Jackson reportedly called propofol, the powerful anesthetic that ultimately caused his 2009 death, his "milk." Charles Czeisler, M.D., Ph.D., from the Division Of Sleep Medicine at Harvard Medical School, testified at the trial against concert promoter AEG Live that the drug interrupts normal sleep cycles and deprives the body of rapid eye movement, or REM, sleep, all while making a person feel as though he or she has had a true night's sleep, CNN reports.
"It would be like eating some sort of cellulose pellets instead of dinner," Czeisler said in his testimony, according to CNN. "Your stomach would be full and you would not be hungry, but it would be zero calories and not fulfill any of your nutrition needs."
Throughout the night, the body cycles through four stages of sleep: three non-REM stages and one REM stage (for more on what happens during each stage, click here). Each complete cycle takes about 90 minutes, typically ending in REM sleep, Phillip Gehrman, Ph.D., clinical director of the Behavioral Sleep Medicine Program at the University of Pennsylvania, tells The Huffington Post. The first REM cycle is fairly short, about 10 minutes, and the cycles get longer throughout the night, up to an hour or so, according to WebMD.
During REM sleep, brain activity looks very similar to wakefulness, Gehrman explains, earning the nickname of "paradoxical sleep." "Your eyes are moving rapidly around as if you're scanning your environment," he says. This is also the dreaming portion of sleep, and the body's muscles are temporarily paralyzed to keep you from acting out those dreams. (That explains why when woken from REM sleep, people sometimes experience a condition called sleep paralysis. Another sleep condition, REM behavior disorder, can occur when that paralysis doesn't happen properly and a person does act out his or her dreams.)
While scientists don't totally understand the function of REM sleep in overall health, it's widely believed to play an important role in memory consolidation and perhaps also in the processing of emotions, Gehrman says.
Propofol, the anesthetic Jackson was taking, is a potent supressor of REM sleep, says W. Christopher Winter, M.D., medical director of the Martha Jefferson Hospital Sleep Medicine Center in Va., who did not evaluate Jackson.
"Propofol induces unconsciousness. There's a difference between being unconscious and being asleep," he tells HuffPost. "Sleep is a whole spectrum process: REM sleep, deep sleep, hormone release. These things may not be happening when you're just unconscious."
Severe REM-sleep deprivation can likely affect mood, concentration, focus, pain tolerance and memory, Winter says. According to CNN, Czeisler testified that lab rats die after going five weeks without REM sleep:
Depriving someone of REM sleep for a long period of time makes them paranoid, anxiety-filled, depressed, unable to learn, distracted, and sloppy, Czeisler testified. They lose their balance and appetite, while their physical reflexes get 10 times slower and their emotional responses 10 times stronger, he said.
But Winter adds a note of caution: When Jackson was on the propofol, REM sleep would have been suppressed at night, but we probably don't know if he was catching any sleep during the day, perhaps nodding off without even realizing it. When the brain is severely deprived of REM sleep, it enters that stage much more quickly, a phenomenon called REM pressure, Winter says.
Both Gehrman and Winter say Jackson's case is unique; the typical patient doesn't need to worry about REM-sleep deprivation. If you think you're not dreaming, it might just be that you can't remember your dreams, not that you aren't having them, Gehrman explains.
"REM deprivation is very hard and it's not something that the average individual, even somebody who has really significant problems with their sleep, really needs to worry about," Winter says.