Washington, Jan 7 (IANS): Parents, please note. If you allow your children to sleep with smartphone, it is time to set "curfew nights" for electronic devices.

According to a study of more than 2,000 elementary and middle-school students, having a smartphone or tablet in the bedroom was associated with less weekday sleep and feeling sleepy in the daytime.

Studies have shown that TV viewing can interfere with sleep but much less is known about the impacts of smartphones and other small screens.

"We found that both sleeping near a small screen and sleeping in a room with a TV set were related to shorter weekday sleep duration," said study lead author Jennifer Falbe from the school of public health at University of California - Berkeley, US.

Children who slept near a small screen compared to those who did not, were also more likely to feel like they did not get enough sleep, Falbe noted.

Small screens are of particular concern because they provide access to a wide range of content, including games, videos, websites and texts, that can be used in bed and delay sleep.

They also emit audible notifications of incoming communications that may interrupt sleep.

For this study, the researchers focused on the sleep habits of children in the fourth or seventh grade.

While kids with a bedroom TV said they got 18 minutes less sleep on weeknights than those without a personal television, that figure rose to nearly 21 minutes for those who slept near a smartphone, whether or not a TV was also present, the study found.

Preteen school-aged children need at least 10 hours of sleep each day, while teenagers need between nine and 10.

Establishing technology ground-rules may help foster healthier sleep patterns, Falbe suggested.

"For example, parents can set night time 'curfews' for electronic devices, limit overall access to all screen time, and/or ban TVs and internet-enabled devices from a child's bedroom," she noted.