Are your kids groggy despite hitting the pillow at a reasonable time every night?

The culprits may be their cellphones or tablets, said Dr. David Holz, a Marshfield Clinic pediatrician.

Staying awake to text, tweet and play games is only part of the problem, he said. Cellphones and tablets can interrupt your sleep even after you’re done using them.

Link between light and sleep chemicals

When it’s dark, the brain releases a chemical called melatonin that helps you fall asleep.

Bright lights emitted from cellphones and tablets cause less melatonin to be released. It takes longer for people exposed to bright lights to fall asleep, and they get fewer hours of sleep per night compared to people who avoid tablet or cellphone use immediately before going to bed.

Light from TVs also can interfere with sleep, but not as much as the blue light emitted by cellphones and tablets, Holz said. Your best bet is to turn both off before bedtime.

Consequences of not sleeping well

Kids who aren’t getting enough sleep may have trouble concentrating, which can lead to poor school performance. They also are at increased risk for mood disorders like depression.

Sleep is important for healthy growth and development, especially in younger kids.

“We always want to encourage practices at home that help children achieve their optimal growth and development,” Holz said. “Promoting behaviors that facilitate adequate sleep are an important part of that process.”

Unplug before bed

Limit cellphone and tablet use an hour or two before bedtime, Holz said. Set a good example by putting your own devices away.

Without electronic lights and sounds signaling your brain that it’s daytime, you and your kids snooze sooner.

Encourage them to read a book or listen to music. Start a bedtime routine early enough so kids get the right amount of sleep for their age.

If possible, keep cellphones off at night or charge them outside the bedroom.

“Although cellphones are an integral part of our lives now, they don’t have to be with us all the time,” Holz said. “Limiting screen time will likely not only improve quality and quantity of sleep, but also improve family communication and strengthen those relationships at home.”