This from Wikipedia:
A lucid dream is a dream in which the sleeper is aware that he or she is dreaming. When the dreamer is lucid, he or she can actively participate in and often manipulate the imaginary experiences in the dream environment. Lucid dreams can seem extremely real and vivid depending on a person’s level of self-awareness during the lucid dream.
You say, you are a lucid dreamer, but it sounds like you don’t have control over your dreams. Do you mean VIVID instead of lucid?
Regarding your state, a lot of things could be going on. The pre-sleep state you describe sounds manic, to me. You could be experiencing the onset of bipolar disorder, or even monopolar mania. If you are, you need to get help before you ruin your life.
Your state of mind and sleep problems could also come from too much alcohol (or other drugs). If you drink alcohol, stop drinking for a week and see if sleep returns to normal. If you can’t stop for a week, you have a problem and we all know what it’s called.
12 hours sleep a day is a lot. Is it possible, that you’re not actually sleeping? If you have sleep apnea, you could find it difficult to sleep and impossible to be refreshed by sleep. You’d wake under that dark cloud and your cognitive functions would experience decline. Is there anyone around you who can tell you if you snore? That could be an indication of sleep apnea, although not everyone with sleep apnea snores. But to be diagnosed, you’ll need to see your doctor and undergo a sleep test.
It’s easy to see sleep disorders as minor fluctuations that we can out wait. But they more often get worse, not better over time. And meanwhile they can ruin our health, our relationships, and out self image. If this continues, get help; and don’t let your doctor take it lightly either.