Phones plugged into bedside outlets, televisions blaring at nighttime and laptops dinging with notifications come as nothing new to teens. Neither is the lack of sleep that tech can cause.

Technology impacts the vast majority of teens, with more than three quarters of teens having access to cellphones and computers.

As of 2013, approximately 78 percent of teens aged 12-17 had a cellphone, and 93 percent had a computer, or access to one at home. Of these technology users, 74 percent claimed to have accessed the internet on their phones, computers or tablets, at least occasionally, according to a study published through The Berkman Klein Center for Internet and Society at Harvard, a research center that focuses on the internet.

The human body has a biological or a circadian clock that is synchronized during the day by the amount of light in the sky. When devices are present, artificial light exposure prevents melatonin, a hormone that controls the sleep cycle, from being produced, due to a disrupted cycle. In other words, the light from laptops and phones throws off your body clock, as stated by the National Institute of General Medical Sciences.

The National Sleep Foundation, an organization dedicated to helping the public improve their sleep through education, agrees.

“The blue light emitted by screens on cell phones, computers, tablets, and televisions restrain the production of melatonin, the hormone that controls your sleep/wake cycle or circadian rhythm,” according to the National Sleep Foundation in the article “Scary Ways Technology Affects Your Sleep”.

When melatonin in the body is reduced, it is harder to fall and remain asleep. According to the National Sleep Foundation’s annual  “Sleep in America” poll,  children and teens who slept with their electronics fully off or not in their room slept significantly longer than those who left them on.

The poll found that cell phones and tablets caused the most damage to sleep schedules, followed by TVs and radios.

Those who left their smartphone or tablet “on” experienced approximately 7.4 hours of sleep, while those who turned it off got 8.3 hours. When there was a TV in the room the average amount of sleep was 7.6 hours compared to 8.3 hours without it. With a radio, it was 7.6 hours compared to 8.3 hours when it was turned off.

This shows that eight hours mostly cannot be achieved if technology is on or present at nighttime, while “Sleep Deprivation in Adolescents and Young Adults” states that adolescents aged 12-17 need eight or more hours of sleep to function at their best.

Even when phones ring, laptops ding, and televisions sound, it’s important to ignore them and power off because technology is hurting your sleep, experts say.