Westchester (IL) - A new study published by the Leuven School for Mass Communication Research at Katholieke Universiteit Leuven in Belgium indicates that cellphone users after "bedtime" may have long-term effects on sleep time.

The study, which included 1656 school children with an average age of 13.7 years in the youngest group and 16.9 years in the oldest group, concludes that late cellphone use is related to increased levels of tiredness after one year. Those who used cellphones less than once a month increased the odds of being very tired one year later by 1.8 ; if the usage level increased to less than once a week, the teenagers were 2.2 times more likely to be very tired. At once a week, the odds increased to 3.3 and at more than once a week even to 5.1. Overall, 35 percent of the cases of being very tired were attributed to the use of the cellphone.

The time of the cellphone use also had an impact on the level of tiredness. Use of the cellphone right after bedtime increased the odds of being very tired by 2.2. Between midnight and 3 am, the odds were 3.9 times higher, and those who used it at any time of the night, the odds were 3.3 times higher.

While this study examined the use of the cellphone in particular, staying up late in general, of course, will have a similar effect, a press release indicated. The American Academy of Sleep Medicine (AASM) recommends people to generally keep computers and TVs out of the bedroom, follow a consistent bedtime routine, establish a relaxing setting at bedtime and avoid foods or drinks that contain caffeine, as well as any medicine that has a stimulant, prior to bedtime.