Schizophrenia often initially appears at a young adult age. Sometimes it is a gradual development in which the person starts to pull away more and more from studies and work and avoids interacting with relatives and friends. The person takes on a changed perception of both themselves and reality. Increased sensitivity to sensory input and strong unexpected emotional outbursts are common, as is a changed sleeping pattern. Sometimes the person's descent into schizophrenia is sudden and without preceding symptoms. The typical symptoms of schizophrenia are hallucinations, delusions, incoherent speech and behaviour, as well as catatonic symptoms, i.e. physical stiffness and getting stuck in certain movements. The hallucinations are often in the form of voice hallucinations. Hearing voices commenting on what one is doing or different voices talking to or arguing with each other are common. Other frequently occurring symptoms include dulled emotions, reduced energy level and becoming increasingly withdrawn.