Sleep.

Yes, apparently getting a decent night's sleep can a difference to how you and your partner are getting on. It's no secret that tempers can get frayed when you're operating on a couple of hours sleep and unfortunately, the closest person to you can often be on the receiving end of this ill-feeling. It's rarely intentional and if you snap at him/her, you're likely to regret it immediately but sleep deprivation can have that negative effect. There's now a study to back this up with researchers from the University of Florida finding that more sleep can improve a relationship. Sixty-eight newly-wed couples were asked to discuss how happy their relationships were in addition to keeping a record of how many hours they slept for seven nights in a row. After researchers conducted "multilevel analysis", they found "that spouses were more satisfied on days after which they had slept for a longer period of time". Obviously, there's a lot more to a satisfactory relationship that how much each person sleeps per night but there's no denying that feeling rested leads to an overall sense of wellbeing. Yet another reason to finally establish a regular sleep pattern... if only it were that easy!