Deneb Variations By Naked Eye?

I was walking outside and looking up just a few minutes ago and was curious what star I was looking at because of how bright it was. Turns out it was Deneb. When I looked back up to identify it it was obviously not as bright as when I first look. It’s a variable star, but my question is is it possible to detect brightness variation with the naked eye? I’m 90% sure it was waaaay brighter the first time I looked at it.