Obstructive sleep apnea can cause lack of REM sleep and, as a result, no dreaming. Symptoms may be such that you have a long sleep period but are prevented from

Obstructive sleep apnea can cause lack of REM sleep and, as a result, no dreaming. Symptoms may be such that you have a long sleep period but are prevented from deep sleep by micro-arousals. Being overweight (as Mr. Arrington mentions in a linked piece) can cause or worsen apnea.