Happiness can be fleeting; if only sadness were as short-lived. If you’ve ever wondered why sadness lingers so much longer than other emotions, sometimes seeming endless, a new study both supports this perception and offers an explanation.

Researchers studied how long various emotions lasted in young participants and found that sadness stuck around far longer than anything else — which may not be surprising, given the prevalence of depression in the general population.

Even anger and stress only lasted a couple of hours, on average, compared to sadness, which typically lasted for several days.

The team asked more than 200 high school students to think about recent emotional events in their lives and to recall how long the emotions lasted. Out of the 27 emotions that were rated, sadness stayed many times longer than any other emotion.

Many emotions were fleeting — shame, surprise, fear, disgust, being moved, boredom, and feeling irritated or relieved — present only momentarily. Even anger and stress resolved in two hours, on average, compared to sadness, which typically persisted for several days.

And interestingly, emotions that seem to be very similar to each other were often very different in how long they were felt. For instance, guilt lasted much longer than shame, and anxiety much longer than fear.

When you think about the results, they’re not so surprising. The duration of an emotion is generally linked to its importance. Sadness carries a lot of weight. It most often is triggered by an unwelcome and potentially heavy real-world event; whereas boredom and irritation are states that aren’t nearly as meaningful, and can end quickly and be easily forgotten.

The results may have relevance for more serious mental health issues, since sadness over an extended period of time and exaggerated through repetitive thoughts, a process known as rumination, can turn into depression.

“Rumination is the central determinant of why some emotions last longer than others. Emotions associated with high levels of rumination will last longest,” said study author Philippe Verduyn in a news release.

So if you’re hanging on to sadness, you’re not alone — it’s natural and logical that it would last longer than other emotions. But if it persists for a very long time, talk with a mental health professional about ways to treat it. Sadness for hours or days is ok; sadness for weeks or months should be treated.

The study was carried out by researchers at the University of Leuven in Belgium, and is published in Motivation and Emotion.