Sunless tans look good on you but can stain your mattress. Photo credit: Getty Images.

That golden glow you get from a spray tan may keep you looking fit and healthy but as one Welsh landlord has discovered, it's not so great for mattresses.

John Winters houses about 400 students in his housing complex in Cardiff, Wales. Four years ago, large orange stains began mysteriously appearing on his mattresses, he said, especially those slept on by female students.

"John [the owner] didn't have a clue what the strange orange marks were. They were roughly body shaped and you could see the wrist, ankle and shoulder areas," housing complex manager Joe Harris explained to the BBC.

After noticing bronzing products in nearly every room, it didn't take Sherlock Holmes to solve the mystery.

The main ingredient in fake tanning sprays is dihydroxyacetone, or DHA, the same chemical responsible for turning the inside of an apple brown when it's exposed to air. When slathered on, DHA reacts with the dead skin cells sitting on the top layer of skin to temporarily darken its color. The color will fade over time as you shed skin cells.

Most products also add a temporary dye to speed up the darkening process. That's the color that washes off when you take a shower or sweat right after a self-tan application. It's also the culprit responsible for the mattress stains.

"Staining can be avoided if you wash the tanning residue off immediately after contact," noted Cassandra Capaci, the manager of the Euro Tans tanning salon in Hawthorne, N.J.

Once a fake tanning spray has set into a material, Capaci said it's tough to deal with. The only thing she's found that works is a vigorous scrubbing with a paste made by crushing up denture cleaning tablets in a little bit of water.

"That might take it off of clothing but I don't know about something the size of a mattress," she admitted.

Capaci said the best course of action is to avoid staining all together by spray tanning earlier in the day so you can shower before bedtime, using thicker, darker sheets and putting a towel between you and the mattress.

In an attempt to solve his problem, Winters has switched to memory foam mattresses with washable covers and said he has begun educating students to wear loose fitting pajamas to soak up the tanning dye. But until the quest for orange tan lines goes out of style, the problem is likely to persist.