I tend to dream each nite but feel very tired after I wake up. Y do we dream n how do I aim 4 dreamless n more rested sleep?

Let's see. Begin with dreaming is very important. We spend 1/3 of our lives doing it. Consider that you are filing short tern memory to long term memory. If a ''file'' related town unmastered developmental phase, the ''personal poetry'' of a dream will leave you with the important residue of such work. Trauma, as in ptsd is noted for this. Since there are other causes, e.g., sleep apnea, get a psych. Veal.
REM sleep. Rapid eye movement sleep is only about 10 minutes in each 90 minute sleep cycle. This is also known as active sleep and this is when we dream. I presume that you have insufficient "deep" sleep that makes up the other 80 minutes of the cycle. You may require a sleep lab to find out if this is true. Most sleep disorders are associated with rem sleep.
Different way. My answer may seem to contradict your wish. I would deliberately seek to dream--change my approach. Think of your dreams as a person who is trying to reach you. The more you push him away, the more persistent he will be. Engage him-after all, he is you-and try to understand what he wants. He is at once creative and constrained: he can't use everyday language. Instead he must use poetic story.