Scrolling through social media or watching an online video before you sleep are activities that could lead to depression or anxiety.
That's according to researchers at Seoul-based Sungshin Women's University, who conducted a study on the effects of "bedtime procrastination."
The use of smartphones was seen as one of the biggest reasons for delaying sleep.
A survey on 106 people in their 20s and 30s showed those who put off their bedtime used their smartphones almost five times longer than the average person.
They also tended to use their devices for an hour longer every day.
"For people who are in their teens or their 20s and 30s a lot of the times what we find is that they're doing things at night before bed that they weren't able to do before during during the day. So for example, socialising, going on their social networks Things like that are all things that they probably needed to do during the day feeling a need for connectedness."
The research team says these pre-bedtime distractions could impact your health and mental well-being, increasing your chance of becoming depressed by 25 percent, and developing anxiety by 14 percent.
Also, activities that delay your sleep increase the risk of insomnia by 41 percent.
And that risk is even higher at 82 percent for those who use their smartphones before they sleep.
To reduce the chance of developing such long-term mental health complications, the research team stresses the importance of keeping a regular bedtime.
"So one of the best things that you could do is wake up at the same time every morning so I know a lot of young people and their sleep schedule is vastly different from the weekdays when they're working.Try to have a wind down time to make sure your mind is turned off and that you are ready you're in the mental space to go to sleep. So there are several things that you could do behaviourally that don't involve medication."
The study was published in the November edition of U.S.-based journal SLEEP.
Through further research, Suh aims to develop an effective treatment that targets the behaviour that leads to bedtime procrastination, and help reinforce healthy sleeping routines.
Oh Soo-young, Arirang News.