This study investigates how brain activity and breathing changes in premature babies when their dose of caffeine treatment is changed or stopped. The study will assess premature babies receiving caffeine treatment as part of their clinical care. Brain activity will be recorded just before caffeine dose is changed and again two days afterwards. Breathing and other 'vital signs' (breathing rate, heart rate, oxygen saturation) will be recorded from the baby's monitor between the recordings of brain activity and for up to two weeks afterwards.