Using smart phones and tablets before bedtime can mess with your sleep. Not only it makes it harder to fall asleep but it also affects how alert you are when you wake up.

A new research from Brigham and Women’s Hospital in Boston, Massachusetts reveal that anyone who uses an eReader, laptop, smartphone, or certain TVs before bed could be placing their life at serious risk. The new study corroborates previous results that you shouldn’t mix screen time and sleep time.

Dr. Anne-Marie Chang, an associate neuroscientist in BWH’s Division of Sleep and Circadian Disorders who was a co-author on the study told the press the effect of using screens before bed time on our hormones. “We know from previous work that light from screens in the evening alters sleepiness and alertness, and suppresses melatonin levels,” she said.

The study directly compared the effects on sleep of reading from light-emitting device against reading from printed book.

As it turns out reading from light-emitting device will make you feel like a zombie, which could in turn make you actually dead pretty soon. Chang stressed that lack in quality sleep can lead to serious health problems like cardiovascular diseases, obesity, diabetes and even cancer.

Using screens before bedtime cuts your sleeping time, which is bad in every perspective.

The researchers examined 12 participants and found out that respondents who used iPad readers took longer to fall asleep. They also felt less sleepy at night and had shorter REM sleep which means that didn’t get a “good night” sleep. The sleep that they had in layman’s term is very low in quality. The result is the complete opposite with those who read with printed books. Moreover, the iPad readers turned out to be tired and stressed even if both of the groups had eight hours of sleep.