What are the possible causes of unrestorative sleep ? can't do a sleep study ?

These and many more: Poor sleep hygiene, sleep apnea, periodic limb movements of sleep, circadian rhythm sleep disorders, pain, narcolepsy, environmental noise, pets sleeping in bed with you, multiple awakenings to urinate, room temperature too hot or cold, uncomfortable bed, inadequate nutrition, drug intoxication or withdrawal, medication side effects, caffeine, alcohol, sexual frustration, most psychiatric illness, .