Read this paragraph from a student essay about the dangers of screen time and answer the question that follows.
[1] Many students use phones and tablets late into the night. [2] This habit has been linked to sleep problems and difficulty concentrating the next day. [3] Research shows that screen exposure before bed delays melatonin release. [4] Many students stay up later without realizing it. [5] They also report feeling more tired and less focused in school.
Which transition phrase should the student add to the beginning of sentence 3 to best clarify the paragraph’s meaning?