insomnia
"Developed acute insomnia immediately following a bad concussion. I would doze off but would wake up within 30 minutes, unable to fall back asleep for hours at a stretch. Tried several sleeping medications (off-label use trazodone, Ambien, melatonin, OTC sleep aids. with no success for several weeks and was getting desperate.  A mere 3mg of Doxepin saved my life. I slept for six straight hours the first night and it only got better and better.  I take 3mg around 9pm, sleep from 11pm to 6am very reliably and have few side effects besides a small amount of weight gain (about five pounds in my first two weeks) and slight drowsiness in the mornings and mid-afternoons.  I'm so grateful to have my sleep back."