Enjoying good quality sleep allows people to think more clearly, be more alert and be at their best both physically and emotionally. The brainstem is the part of the brain that plays a key role in controlling the sleep-wake cycle. Sleep disorders/problems are common in the brain-injured population. Many patients sleep a great deal, while others really struggle to get to sleep and/or to get good-quality sleep. Patients with brain injuries generally require some extra sleep and rest - particularly in the weeks and months following the injury. Some people experience great difficulty falling asleep. This problem is known as insomnia. Sometimes it is not the ability to fall asleep that is the problem, but rather the ability to stay awake during the day. This problem is known as narcolepsy. Parasomnias are a group of sleep disorders, including night terrors, that are characterised by certain abnormal behaviours, movements, emotions and perceptions that disturb sleep.