The moment my husband and I were married, someone offered the advice: never go to bed angry. I took that advice to heart. We didn't argue much at all during the first year of our marriage, but realized quickly that arguments only escalated at night when we were both irritable and exhausted. We decided after that first year to "ignore" that advice, and save disagreements until the morning. Usually we were ready to apologize by the morning and calmly discuss how to reconcile our differences in opinion.
I just found this article in the NYTimes Health Blog, Well: Really? The Claim: Never Go to Bed Angry. Scientists actually found that "going to sleep after experiencing negative emotions appears to reinforce or "preserve" them." However, in this study people were shown images that would elicit certain emotionsl they were not involved in disagreements with their spouses. I would argue that these are much different experiences. The article also mentions other studies that have shown that "sleep, perhaps as an evolutionary mechanism, enhances emotional memories." Isn't that interesting? I have to admit that I have never felt like my emotions were actually "protected" or "preserved" during sleep. I am guessing that maybe I am just so sleep-deprived, (and have been for about 10 years now), that no matter what, sleep makes me feel wonderful, and helps me to act much nicer (and less emotional) around those I love.