Australian actor Heath Ledger passed away Tuesday afternoon in what is believed to have been an accidental drug overdose. According to his housekeeper, he was still alive and snoring at 1 p.m., but by around 3 p.m., his body was cold. What happens when you overdose on sleeping pills—do you fall asleep and then die later?
Yes. When someone overdoses on sleeping pills, they first feel drowsy, as if they had taken the prescribed amount. Then they fall asleep, enter a coma, and, if the dose is high enough, stop breathing. Someone who overdoses on sleeping pills probably won't have a dream before he dies, but it's not out of the question. This is because the state induced by the drugs isn't exactly like the natural rest many of us get each night. Doctors believe sleep aids actually disrupt the normal cycle of sleep and decrease the amount of REM sleep, which is the stage during which we dream.
Police reportedly discovered several kinds of prescription pills at Ledger's apartment, including Ambien sleeping pills, a packet of Zopiclone, and generic versions of Xanax and Valium. Drugs like Ambien and Zopiclone are known as sleeping pills, while Xanax and Valium are often called anti-anxiety medications, but they all do pretty much the same thing. You might need 5 milligrams of Valium to calm down when you're anxious, but that same amount could put you to sleep if you were more relaxed. Others might need a lower dose for anxiety and a higher one for sleep. The drugs interact with brain receptors for GABA, the main neurotransmitter for quieting, or inhibiting, neurons. As a result, each cell becomes more sensitive to the GABA signal and less likely to fire off an electrical pulse. This produces a general suppression of brain activity and makes us fall asleep, but too much suppression can push a person past sleep and into a coma. In a drug overdose, deep sleep and coma actually exist in the same continuum of brain activity. Patients in mild comas, for instance, may still open their eyes or talk. (Antihistamines like Donormyl—which was also found in Ledger's apartment—are used as sleep aids, too, but act in a different way and involve other risks.)
Lying around in a comatose state doesn't automatically kill you, but the dangers mount as your brain shuts down. If the respiratory center in your brain doesn't receive enough stimulation, the body forgets to breathe. A healthy person normally takes 12 to 20 breaths per minute, but this can drop to below 10 breaths a minute, and shallow ones at that, in an overdose. Without enough oxygen, the heart may beat irregularly and blood pressure may drop. Respiration will eventually stop altogether, but even before this occurs the individual may choke on his own saliva or tongue. Depending on your body's ability to absorb the drugs, the whole process could take several hours. If you mix the drugs with alcohol or ingest them in a liquid form, death can arrive much sooner.
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Explainer thanks Steven Curry of Banner Good Samaritan Medical Center, Paul Doering of the University of Florida College of Pharmacy, and James Rhee of the University of Chicago.