How your boyfriend, girlfriend, or spouse can influence everything from sleep to blood pressure.

For better or worse

Can your relationship status make a difference in your overall well-being? To borrow a commonly used Facebook phrase, it's complicated. Research shows that strong partnerships can help us avoid illness, adopt healthier habits, and even live longer. On the other hand, troubled relationships tend to breed stress and weaken immunity.

So many factors affect our health, whether it's the behaviors we exhibit toward each other or the habits that we pass on to each other," says psychologist Maryann Troiani, PhD, co-author of Spontaneous Optimism. So whether you're dating casually, shacking up, or already married, keep in mind these 12 key ways your romantic bond may influence your mind and body.