Delirium is a serious change in mental abilities. It results in confused thinking and a lack of awareness of someone's surroundings. The disorder usually comes on fast — within hours or a few days. Delirium can often be traced to one or more factors. Symptoms Symptoms of delirium usually begin over a few hours or a few days. Symptoms often come and go during the day. Symptoms tend to be worse at night when it's dark and things look less familiar. Reduced awareness of surroundings. This may result in: • Trouble focusing on a topic or changing topics • Getting stuck on an idea rather than responding to questions • Being easily distracted Poor thinking skills. This may appear as: • Poor memory, such as forgetting recent events • Not knowing where they are or who they are • Trouble with speech or recalling words • Rambling or nonsense speech • Trouble understanding speech • Trouble reading or writing Behaviour and emotional changes. These may include: • A short temper or anger • A sense of feeling elated • Lack of interest and emotion • Quick changes in mood • Personality changes • Seeing things that others don't see • Being restless, anxious or combative • Calling out, moaning or making other sounds