Title: Shifts. Sentence 1: Since Elana moved back home, she and her sister have shared a bed. Sentence 2: They're both very tall adults and the bed is just full-sized. Sentence 3: When the weather warms, they find it hard to both sleep at once. Sentence 4: Eventually they settle on two shifts, morning and night.
Elana sleeps during the day, but they always have breakfast together.