...She had been learning this, and relearning it each day – that these cycles of waking and sleeping had a sort of looking pattern, meaning that whatever occasions for sleep were issued could be counted on coming round again, eventually…
-- Narrator (The Sounding and the Landing in the Living Room paragraph N/A)

Importance: Helen spends a lot of time trying to get Rose to sleep. Sleep is essential for a newborn, but it is also important for Helen because she can really only relax when the baby is asleep. The fact that Helen is learning that wake and sleep are cycles for a baby gives us more information about what she believed before than what she believes now because the fact that she learned there is a cycle shows that before she was doubting it, likely believing that each difficult stage would last forever.

It was remarkable to her – exhilarating and exhausting – how many times this could happen: how many adjustments a person could...
-- Narrator (The Sounding and the Landing in the Living Room paragraph N/A)