The Ages When Staying Single Starts Hampering Mental Health

Study Explains How Being Single At 26 Affects You Differently Than At 18

At what age does being single begin to extract a mental toll? Research tracking nearly 17,400 young adults has found a clear timeline for when prolonged singlehood starts taking a toll on well-being. The pattern is more specific than many would expect.

Scientists from the University of Zurich analyzed three massive studies in Germany and the UK, following people from age 16 through their late twenties. They discovered that never having been in a relationship affects life satisfaction, loneliness, and depression symptoms at different ages, and in ways that get worse as the years pass by.

Here’s what the study, published in Journal of Personality and Social Psychology, found: at 16 or 17, very small differences existed between single teens and those who’d eventually find partners. Nothing clearly separated the groups yet in terms of happiness, loneliness, or depression.

The Decline Starts at 18

By age 18, things shift. Young adults who stay single start experiencing steeper drops in life satisfaction (how happy people feel with their lives overall) compared to peers entering relationships. It’s not a huge gap yet, but the paths have diverged.

Then at 19, loneliness kicks in differently. Singles start feeling more isolated and disconnected. Both groups experience some loneliness as they navigate this life stage, but singles climb higher and faster.

And here’s the kicker: these gaps don’t level off. They keep growing throughout the twenties.

After 24, Things Get Worse

The mental health costs of staying single ramp up noticeably after age 24. Loneliness spikes sharply. Life satisfaction keeps dropping. The space between singles and partnered young adults widens year after year.

Depression symptoms follow a slower timeline. The gap starts showing up around age 23 and continues through the mid-to-late twenties, but it’s not as steady or as strong as the loneliness pattern. Through the early twenties, both groups see depression increase at similar rates, but around age 23, singles start pulling ahead.

Why does depression lag behind? The researchers think concerns about being single and feelings of loneliness might come first, then snowball into broader emotional distress as singlehood stretches into the late twenties.

By age 29, the cumulative impact was clearest for loneliness, and still noticeable for life satisfaction. Depression differences showed up earlier in the later twenties, but weren’t as consistent by 29.

Researchers theorize one likely explanation for these patterns is the tendency for social pressure to ramp up as 30 gets closer. Dating in high school or college is normal, even expected. At the same time, nobody blinks at a 19-year-old who’s never been in a relationship.

But approaching 30 without any romantic relationship experience? That’s increasingly unusual in Western cultures. The researchers suggest social expectations may play a role here, as norms around partnering, marriage, and parenthood all grow stronger as one’s twenties wind down.

Interestingly, people who found their first partner later in life (mid-to-late twenties) experienced bigger immediate happiness boosts than those who partnered younger.

The Vicious Cycle

The research revealed what the authors suggest is a “vicious cycle.” Being less happy, more lonely, or more depressed as people moved through their late teens and twenties made it harder to find a partner in the following years. And staying single longer? That drove happiness down and loneliness up even more.

The cycle feeds itself: singlehood decreases well-being, which makes finding someone harder, which extends singlehood further.

Crucially, well-being at 16 or 17 didn’t predict who’d stay single long-term. The effect showed up from well-being levels later in the twenties. So this isn’t about gaining dating experience early in life, it’s about how things unfold over time.

Men stayed single longer than women. College students and graduates stayed single longer than people with less education, possibly because they’re prioritizing school and early career moves over relationships.

Your Basic Demographics Don’t Change Much

The researchers tested whether gender, income, education, or living situation changed these patterns. The answer was basically no. Single men and women showed nearly identical trajectories. More money didn’t change the pattern. More education didn’t either. There were a few small exceptions at specific ages, but the big picture stayed the same.

That doesn’t mean nothing helps in real life, just that these background factors didn’t explain away the trend. The well-being costs of extended singlehood seemed to hit almost everyone similarly, suggesting this taps into something fundamental about human needs for intimacy and connection.

For people who did enter their first relationship during the study, the changes were immediate. Happiness went up, loneliness went down, and those benefits stuck around through age 29, even when people experienced subsequent breakups. The first romantic partnership appears to be a uniquely important developmental milestone.

Depression, though, barely budged when people partnered up. The researchers think different aspects of well-being might work through different mechanisms, with depression being more stubborn.

What This Actually Means

This research does not mean one must be in a relationship or that being single for too long is a disaster. Plenty of single people are perfectly happy with their lives. The differences here, while real and consistent, weren’t life-ruining.

Still, the findings do highlight specific ages when staying single gets harder on mental health. The late teens are when the paths first split. The early-to-mid twenties are when the gaps grow. And the later twenties, especially after 24, are when things accelerate, particularly for loneliness.

For anyone in their late teens or early twenties reading this, the takeaway isn’t to panic and download every dating app. It’s that small well-being deficits that show up now can compound rather than stay stable. And if you’re in your mid-to-late twenties entering your first relationship? The research shows such a milestone still delivers real benefits, even if delayed.

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Disclaimer: This article discusses research findings about statistical patterns in large populations and is not intended as personal medical or mental health advice. Individual experiences with singlehood vary widely, and many single people report high levels of well-being and life satisfaction. If you’re experiencing depression, loneliness, or other mental health concerns, please consult with a qualified mental health professional. Relationship status is just one of many factors that can influence well-being.

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