Does Hershey's cocoa powder contain caffeine?

I checked the ingredient list on the container and it only says "cocoa." I know chocolate has caffeine so I'm thinking it does... I've been having trouble sleeping lately, and I wasn't thinking when I mixed a little bit of cocoa powder into my hot soy milk a little while ago. How much caffeine do you think it has, and do you think a little bit of it in milk will keep me awake tonight?