by AsymmetricalCoupling
The inability to dream, not just remember your dreams, is an actual condition frequently caused by damage to the brain, and often by stroke. Persons who do not dream wake frequently through the night, and despite having slept for 8 hours wake feeling exhausted. Lack of REM sleep is detrimental to one's health. If you do dream but do not remember it none of this symptomology arises.
Sociopaths do dream and may frequently wake without remembering. I have occasional dreams which are frequently very vivid. Most of my dreams are nothing more than a single feeling and a few images, occasionally I do have dreams that play out like a story and those are generally extremely bizarre. The other night I had one. I was with my younger brother. We were robbing a house together. We've never even talked about doing something like this together, and we rarely even talk now.
I used to dream when I was much younger. But now I exhibit symptoms of what you've described above (Waking throughout the night and feeling exhausted after a full night's rest). 8 hours of sleep feels like 2 hours of sleep, and 2 hours of sleep feels like 2 hours of sleep, so I generally just sleep 2 hours to avoid wasting valuable time in unconsciousness. I do not dream anymore (I guess an argument can be made that I simply can't remember the dreams), at least, visually. I recall "hearing" incoherent sounds, ones that aren't really imaginable, during my sleep. Maybe, once or twice, have I actually heard a coherent sound in the past many years. A friend of mine told me I seemed like I was a narcoleptic, but narcoleptics are noted as VERY vivid, and constant dreamers. I fall DEEP into sleep VERY quickly, compared to the people around me (I slept through my house being on fire, shortly after I fell asleep AND the Fire Department putting the fire out), much like a narcoleptic. I have fallen asleep mid-day, in the middle of holding things, for example. But this has been a somewhat recent development. And, these sleep attacks can also be due to the sleep deprivation associated with my insomnia. However, insomnia does not explain the quick sleep cycles.
I recall having a few vivid dreams when I was much younger, but most of the time, if I remember correctly (I usually don't), they mostly consisted of a single image or sound (Only that image/sound for the entire night. As in, that would be the ONLY thing I would experience, for that moment, and the rest of the night would be completely devoid of dream activity.).