Thanks for that additional information.

What you are describing is a condition called excessive daytime sleepiness (very creative name, don't you think?) This is a condition with multiple causes. The most common cause is from a primary sleep disorder followed by medications and then medical problems.

Primary sleep disorders are problems like obstructive sleep apnea, narcolepsy, RLS with periodic limb movements, and insomnia. Sleep studies are very helpful in diagnosing these problems. Although you do not have sleep apnea, you do have RLS/PLM. RLS makes can make it difficult to fall asleep, the PLM's will often wake the individual, although they frequently don't remember this. Insomnia and narcolepsy can be diagnosed with the time that it takes to fall asleep. I would pay careful attention to the sleep study report for sleep latency and the index of awakening (forgot the name). A short sleep latency supports narcolepsy, a high awakening index would suggest that the limb movements are disrupting your sleep.

Medications could also be a cause. Studies have shown that after about 4 months, benzodiazepines (like Xanax) alter the sleep architecture. Normal sleep has 4 stages of sleep followed by a REM cycle. After time, benzodiazepine use eliminates stage 3 and 4 sleep. These are the stages responsible for resting the mind. Even though your body is rested, your mind is not. I would re-evaluate your need for Xanax with your psychiatrist.

Not a definitive answer here, but as you can see, there is a wide variety of possible causes. Let me know if you need any clarification.