No girl wants wrinkly cleavage, as it can age you more than anything.
Dita Von Teese says her greatest beauty secret is to stay away from sunshine: "I never go sunbathing. My worst fear is looking down and seeing brown, wrinkly cleavage. It will get white and wrinkly, but there is no need to rush it." (source)
Wrinkles between and above the breasts are caused by sun damage, so wear sunscreen, but wrinkles can also be caused by your sleeping habits, especially if you sleep on your side.
I’m not too sure if I’d use either of these products but they’re out there if your afraid of cleavage wrinkles!
There is the The Intimia™ Breast Pillow. it’s a bit like a bra but with out the cups and it doesn’t matter what position you sleep in it moves with the body.
The second product is Kush support and it seems like you have to be a true-side sleeper for it to work!