dreams/waking/turnaround

How can it be that I can go to bed last night in a calm and peaceful mood and then wake up this morning feeling dark and filled with dread? Harbinger of sinking...was it my dream? Did I have some disturbing dream, a waking of some memory, that will bring me down and which, awake, I cannot remember? I used to let my moods be, let myself swing wildly and sometimes dangerously from high to low. Now I must try and exert some control. But perhaps this is wrong; I could just give in. In the past, if I woke up feeling like this, I would go back to sleep and let the day pass. But I can't do that today; I have to teach, I have things to do. But what I really want to do is let the day pass with my consciousness on hold.