Question

does the text contain a vague pronoun reference?
they have discovered that sleep has more than just restorative functions. for example, it plays a significan role in strengthening and solidifying memories.
yes no

Explanation:

The pronoun "they" is used, and it's not clear from the given text who "they" refers to (no prior context about who "they" could be), so there's a vague pronoun reference.

Answer:

yes