Ever since I was young I've had intermittent nightmares. They've decreased in frequency since I've got older, but are still there and are usually pretty vivid. David has learnt to cope with them - usually he doesn't wake me when the shouting starts, but calms me and I go back to sleep. Sometimes I don't remember them, sometimes I have a vague recollection that something's happened and other times I remember them distinctly in the morning.
Last night was a nightmare night. I dreamt that someone was in the room and lay down on the bed on the opposite side of me to David. The confusion and shouting started and I got out of bed, I think to try to switch on the light to prove what I knew in my head was happening. Of course I couldn't find the light switch (I always expect it to be by the bedroom door, but it's been put next to the walk-in wardrobe door) and when David switched the light on (as it was obvious that saying soothing words wasn't going to get me to just go back to sleep) there of course wasn't anyone there. With the turning on of the light and the realisation that the extra person in the bed was a figment of my imagination I woke up properly and was completely confused about what was going on and the emotions I was feeling. My heart also started racing - in fact I don't think I've ever felt it race so fast or so hard.
These nightmare episodes are very strange and I wonder why I get them. Why do I "wake up" in the night shouting and David doesn't (he just gets woken up by me)? What makes my brain convince itself that something is happening that isn't?