A study in Sweden on 21 youngsters between 14 and 20 showed that teenagers who excessively use their cell phone are more prone to disrupted sleep, restlessness, stress and fatigue.

The findings, which were presented at SLEEP 2008, the 22nd Annual Meeting of the Associated Professional Sleep Societies (APSS), found that such youths also had more 'careless' lifestyles, consumed more stimulating drinks, suffered from disrupted sleep or insomnia and were more susceptible to stress and fatigue.

"Addiction to cell phone is becoming common.

Youngsters feel a group pressure to remain inter-connected and reachable round the clock. There seem to be a connection between intensive use of cell phones and health compromising behaviour such as smoking, snuffing and use of alcohol," said Gaby Badre of Sahlgren's Academy in Gothenburg, Sweden, the author of the report.

"It is necessary to increase the awareness among youngsters of the negative effects of excessive mobile phone use on their sleep-wake patterns, with serious health risks as well as attention and cognitive problems," Badre was quoted as saying in a report by the Science Daily online on Tuesday.

The scientist said adolescents should get nine hours of sleep a night.

Studies have also linked the use of mobile phones by pregnant mothers to birth of kids with behavioural and emotional problems.

In a study at the universities of California, Los Angeles (UCLA) and Aarhus, Denmark, researchers surveyed more than 13,000 children and found that using mobile phones even two or three times daily was sufficient to increase the risk of their babies developing hyperactivity and difficulties with conduct, emotions and relationships.

The health implications likelihood is even greater if the children themselves used the phones before the age of seven.