Sometimes dreams are terrifying, but they are usually a collection of scattered, confused thoughts. If you dream about something that is worrying you, you may wake up exhausted sweating, and with a rapid heartbeat. Dreams have positive effects on our lives.
In this paragraph, what does "they" refer to? In my opinion, as a pronoun rule, it refers to "dreams". But ,in the sense of context, it could refer to "terrifying dreams". Please share your opinions with me.