What is the potency of expired sleeping pills?

What is the potency of expired sleeping pills?

Is it still enough to OD from?
Knock someone unconcious?

I’m doing research for a novel. If you’re wondering.
If anyone could refer to any sites with info on this subject, would be highly appreciated.

It depends what kind of sleeping pills, I would imagine. Can’t you just make up a brand of hypnotic, like Stephen King did with the narcotic pain killer Novril in Misery that suits the purpose of the story?

Sweetie. If you can’t follow up on threads you open such as http://boards.straightdope.com/sdmb/showthread.php?threadid=133152
then don’t even start 'em.

Given the complexity of modern pharmaceuticals a reduction of potency is not the only possible change to anticipate if you use drugs beyond their safe storage period. An increase in potency , or an entirely unrelated effect is possible as well.

Tris