Washington: Teenagers addicted to their mobile phones tend to experience disrupted sleep, restlessness, stress and fatigue, according to a new study.

The study, authored by researchers at the Sahlgren's Academy in Gothenburg, Sweden, focused on 21 healthy subjects, between 14-20 years of age, with regular work and studying hours and without sleep problems.

The subjects were broken up into two groups: a control group (three boys, seven girls) and the experimental group (three boys, eight girls).

The control group made less than five calls and / or sent five text messages a day, while the experimental group made more than 15 calls and / or sent 15 text messages a day. The subjects were then asked questions regarding their lifestyle and sleep habits.

Compared to subjects with restricted use of cell phones, young people with excessive use of cell phones (both talking and text messaging) had increased restlessness with more careless lifestyles and more consumption of stimulating beverages.

They also had difficulty in falling asleep and had disrupted sleep and were more susceptible to stress and fatigue. In fact, their behaviour suggested a delayed biological clock.

"Addiction to cell phone is becoming common. Youngsters feel a group pressure to remain inter-connected and reachable round the clock," said Gaby Badre, who led the study

"They start using mobile phones early in life. There seem to be a connection between intensive use of cell phones and health compromising behaviour such as smoking, snuffing and use of alcohol," he added.

The findings of the study were presented on Monday at SLEEP 2008, the 22nd Annual Meeting of the Associated Professional Sleep Societies. IANS