restless legs syndrome
"Initially, was prescribed 400mg to take at night. It worked great for two weeks. I slept like a baby. But it stopped working and restless leg symptoms returned so I took double dose (800 mg). So far so good. I wake up refreshed.  I used to be such a grouch in the morning for most of my life.  I cannot take during day because it makes me sleepy. If I take a nap I take a 400 mg tablet. I love it."