It’s pretty common behavior for young adults. They’re often night owls. A 9 p.m. bedtime for someone under the age of 25 is about as ordinary as a skateboarding 70-year-old.

Scientists, however, have recognized that young people who burn the midnight oil appear to be at higher risk of substance abuse and mental health disorders. It hasn’t been entirely clear why that is.

But British investigators have now associated that higher risk with impulsivity among those ages 18 to 25.

The researchers sought out 200 young volunteers to better understand the phenomenon. All were quizzed on their sleep patterns. Did they avoid the pillow until the wee hours or hit the sack at a time their moms would have found reasonable?

They were also questioned about sleep quality, anxiety levels and impulsivity, in addition to how much they smoked and their consumption of alcohol, coffee and other caffeinated drinks.

A computer program set out to establish their impulsivity levels. Each volunteer was gauged on how long they were willing to wait for a hypothetical cash reward. The more impulsive in the group tended to snatch up smaller, immediate rewards rather than being a little more patient to get a larger reward later.

It turned out that the participants who liked to stay up late were more impulsive than their daylight counterparts. They also reported being more anxious, and drank and smoked more.

So, being impulsive might be a link to such detrimental behavior. The study’s authors say bolstering sleep hygiene could improve the mental and physical well-being of an at-risk population.

Good sleep is good medicine.