You've been friends with the guy down the street since the sandbox -- but now he's very attentive toward you. Or, your cute lab partner smiles at you a lot, and you like it. When your friend starts spending a lot of time with you -- just to be near you, and it makes you feel tingly -- these are signs of sexual attraction between friends. It's natural -- and common, says Dr. Laura Berman, in an article for the Chicago Sun-Times. Berman cites a survey from the University of Wisconsin-Eau Claire, in which researchers questioned more than 400 people from age 18 to 52 about their friendships with the opposite sex. Many answered that they felt some sexual attraction toward their opposite-sex friend.

The Eyes Have It

He looks up from his library book just to see if you're looking his way. Your eyes meet and you can't seem to take your eyes off him, as if you're glued to each other. When you're in a room full of people -- maybe it's the college mixer or a club, but he doesn't notice the room is full of people (and neither do you). Yep, these are signs of sexual attraction. And when you' re talking with him -- he leans close and all you see are his eyes. You feel pulled toward him and you don't want to break away, and it seems he feels the same way. You might see him look at your mouth and then he’ll look back up at your eyes. He might smile and his eyes will look soft. This is a strong signal that he is attracted to you and might want to kiss you, according to Judi James, author of The Body Language Bible, as cited on eHarmony.com.

Body Language Doesn't Lie

When you're with her, she smiles a lot and leans in toward you. She might touch you on the shoulder or on the arm -- seemingly for no reason other than to be near you and touch you. Her body and voice seem relaxed, not tense. She will stand tall and her body will incline toward you -- not away from you -- when she talks. Likely she will nod when you nod, and she might unconsciously mirror -- or copy -- your movements. If you cross your legs while sitting, she might do the same. If you tilt your head, she might tilt her head. Mirroring isn’t deliberate -- it happens when people are attracted to each other, says James.

He Laughs at Everything You Say

He laughs at your jokes -- all your jokes, and seems sincere, as if he genuinely thinks you're funny. You're funny, but you didn't know you were that funny. He likes to be around you, and finds you fascinating, and your jokes strike him as original. If you're flattered by her liking your jokes and this makes you want to be around her more, then it's part of a chemistry you share -- that inexplicable sexual tension that's more than "just friends." When this magnetic chemistry develops further, you and he start communicating in a secret code, known only to you two.

He Wants to Be Around You -- All the Time

A bunch of subtle and not-so-subtle signs a friend is attracted to you are that he makes himself available to you -- anytime. He doesn't mind if you call him in the middle of the night, just to talk. He seems vulnerable, and you find that endearing. He truly wants to be a part of your world. He may go out of his way to help you -- or to help your family. He reveals his budding romantic interest in you if you mention a guy you like. He might respond with reasons why that guy is not good enough for you. Basically, he won't think any guy is good enough for you, unless it's him. He holds you in high regard and doesn't want you to like someone he feels doesn't deserve you. Underneath, he's probably attracted to you as more than a friend and hopes you feel the same way.