We underestimate others' blue moods.

Ever go to a holiday party where everyone seems extra cheerful and wonder if you’re the only one battling holiday blues?

In this study, researchers looked at how accurately we estimate the frequency of others’ negative emotions. Participants guessed that others experienced far fewer negative emotions than they actually did and assumed that others’ emotional lives were better than they really were—even with close friends!

The effect is essentially perception bias: In social settings, we tend to keep our true feelings hidden behind a smile. That makes it easy to assume that others are always happy, since we’re only privy to our own emotional turmoil.

But watch out: Results showed that those misperceptions led to greater loneliness, brooding, and dissatisfaction with life. When you feel like you’re the only one wading through life’s ups and downs, remind yourself that the grass is rarely greener.

Loneliness feels awful, and it’s a bummer for beauty too. In fact, it prematurely ages the body and leads to higher levels of stress (which is bad news for your skin, hair and mood). Next time you hit a rough patch, share your true feelings with a close friend. Misery really does love company.