Symptoms of psychosis dropped in 25 percent of a large group of students who signed up to six 20-minute sessions of cognitive behavioural therapy (CBT) directed at tackling insomnia.

Oxford University research involving almost 4,000 participants found the therapy also benefited 20 percent of people living with anxiety and depression.

Taking into account effects not linked to treatment, insomnia in the CBT group fell by almost half 10 weeks into the study.

“The dominant view is that sleep [problems are] either a symptom of several mental health problems or it is a secondary consequence,” said Daniel Freeman, co-author of the research from the University of Oxford. “Really, sleep is one of the contributing causes.”

Most participants did not have clinically diagnosed mental health disorders.

“The realistic view of mental health problems is that there is a spectrum of severity and all the evidence we have is that the causes and the treatments are similar across the spectrum,” added Freeman.