A few things that can wreck a good night's sleep? Caffeine, sure. Stress and anxiety, definitely. Being in a relationship? Well, yes, now that you mention it.
Specifically, it's the bed-sharing that messes things up. Simply put, sharing a bed means waking up more. In one 2007 study, nearly half of participants reported that they'd been woken up by their partner's movements, noises, or activities.
This presents an unfortunate predicament: You want to be able to sleep through the night, but you also want to keep on sleeping next to your partner. Ultimately, research suggests, most people end up choosing the latter, either because it's what's expected of couples or because they believe it's better for the relationship.
-The Week
