Insomnia

A persistent difficulty initiating or maintaining sleep, despite adequate opportunity, resulting in clinically significant daytime impairment or distress. Common causes are stress, anxiety, depression, poor sleep hygiene (daytime napping, TV in bed), substances (caffeine, nicotine, alcohol), jet lag, shift work, chronic pain, GERD, hyperthyroidism, heart failure, restless legs syndrome, sleep apnea, and medications (steroids, antidepressants).