Dr. Charles Czeisler, a Harvard Medical School sleep expert who testified Friday at the wrongful-death trial of concert promoter AEG LIve said the medicine Dr. Conrad Murray had been providing Jackson to treat his insomnia prevented the pop star from getting REM --rapid eye movement -- sleep which is essential to keep the brain and body alive.
"The symptoms that Mr. Jackson was exhibiting were consistent with what someone might expect to see of someone suffering from total sleep deprivation over a chronic period," Czeisler said.
A few members on Jackson's staff have testified that during his last days the singer exhibited odd behaviors including forgetting the lyrics to some of his most famous songs, talking to himself at times and paranoia.
"I believe that that constellation of symptoms was more probably than not induced by total sleep deprivation over a chronic period," Czeisler testified.
Czeisler added that Propofol, the drug that Murray was providing Jackson, disrupts the normal sleep cycle by making the patient feel rested even when they're not getting any REM sleep.
If the singer had not died of an overdose on surgical anesthetics on June 25, 2009 the lack of REM sleep on his system may have cost him his life within days anyway, Czeisler said.