Why more dosage of sleeping drugs are more danger than more dosage of normal drug?

Remember heath ledger's death, main cause is more dosage of sleeping drug.

Edited December 29, 201411 yr by Ganesh Ujwal

I'm going to guess at this, and say it's probably because unconsciousness is involved. If you're not in bed when you take them, you run the risk of being overcome by sleep at a time when it's dangerous, like walking down a staircase, or working with the stove, or near sharp objects.

 

I think there's also a danger of becoming too artificially relaxed, which can cause breathing problems, and you're unconscious so you can't do anything about it. Iirc, Heath Ledger had 3 or 4 different sleep meds in his system, or a couple of sleep meds and pain killers that make you drowsy.

Why do you think sleeping drugs are more dangerous than others?

As far as I can tell, the therapeutic index for hypnotics isn't particularly low.

http://en.wikipedia.org/wiki/Therapeutic_index