Talk to your primary care about it. A sleep study can help to see if there is any sleeping disorder.

If this is becoming a real problem and affecting your functioning, then you may want to be evaluated by a psychiatrist for depression and ADHD.

If you have history of trauma it could be related to you having PTSD which is comorbid to depression and negative thoughts during the day.
Please get a psychiatric evaluation.
Thank you and all the best.

Daydreaming may occur to cope with various life stressors, anxiety, boredom, inattentiveness etc... I recommend keeping a journal of what induces you to daydream and what type of comfort it provides for you. If it persists and you are spending a lot of time daydreaming and not getting your work done or avoiding social interactions then I recommend seeking help via a therapist.

There is nothing wrong with vivid daydreams...unless they are interfering with life. A person with a vivid imagination is usually a creative person. If this is a source of distraction or loss of focus, you may be deficient in norepinephrine in the brain. L-tyrosine is the amino acid that turns into dopamine and norepinephrine in the brain, but you have to take P5P (pyridoxal-5-phosphate) with it. Get an enteric form of P5P.

There is nothing wrong with vivid daydreams as long as it does not interfere with your ability to function daily. I suggest that you allow yourself a specific period to indulge in it and stick to the timeframe. Another way, is to write your daydreams in a journal.

Get assessed for attention deficit disorder. Also read "Self Therapy" by Jay Earley, and perhaps books on hypnosis.

Evaluation by a mental health professional.

Talk with a therapist to find the reason to have vivid dream