Something just isn't right...

Lately (last few weeks) there has been something wrong in my life, but I can't even imagine what exactly. It's really annoying.

Work hasn't been stressful lately, the social life has been normal (that is, rather active), nothing bad is happening, I don't have a tendency to get depressed during the dark time of the year, the whole thing does not feel like a depression anyway (energy, libido and appetite are all normal), I am AFAIK not sick, not in love and don't have any spiritual cravings.

Nonetheless I am having trouble falling asleep, keep seeing rather nasty nightmares almost every night, and have this feeling that there is something wrong that needs my immediate attention and I have to find out what it is.