A major new international study has found a link between sleep disturbance and psychiatric disorders.

The study of 91,000 people was carried out by Lancet Psychiatry and saw an increased risk of depression, bipolar disorder and other mood problems among people who experience consistent sleep disturbance.

Walter McNicholas is president of the European Sleep Research Society and a consultant in the sleep laboratory at St. Vincent's Hospital. He says that phone use at night is "a well-recognised practice that contributes to sleep disturbance."

"Modern lifestyles contribute to poor sleep habits. People tend to sleep less and spend less time in bed."

Walter says seven to eight hours of sleep per night is the ideal amount, and if people achieve this consistently during the week, they will have no need to sleep later than usual at weekends.

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