Day-nap-mares

Does anyone else get extraordinarily horrible dreams if they sleep during the day?

While sleeping at night, the way God, or Mother Nature, or our Insect Overlords intended, I either blissfully sleep without dreaming or have wonderful dreams involving happiness, people I love or want to love, superpowers I will one day have, comfortable surroundings and horrible deaths for my enemies at my hands or the hands of my dog warriors and cat Viziers. Generally I am with someone I miss, or perhaps living out a future I desire. Of course, there are the occasional dreams that are surreal and have no bearing on life itself. There is this one about a paperclip embedded in an old lady's thigh that I have every 5 years or so. I usually push the paper clip, experience abject terror and then wake up, my heart about to burst. Oh, and there is a tree. Those notwithstanding, my night time dreams are generally very happy.

If I take a long nap during the day, however, my subconscious punishes me with the most horrific nightmares I experience. Usually involving horrible violence or the ruination of my life as I know it. I've killed my entire family, commited suicide off a bridge (to prevent a curse..), been tortured, taken hostage, failed out of any of my endeavours, witnessed the deaths of people helplessly, died a lonely old man, etc during these day-nap-mares. They don't happen all the time, but almost exclusively they occur during a day time nap. Isn't that strange?

So usually day naps put me in a bad mood.