Male 48 fall sleep around 10:30 pm wake up around 3 am go to bathroom and can't get to sleep again, it happens once in a while, stop drinking liquids at 7 pm, what could it be?

Maybe bph : New onset of waking in the middle of the night to urinate could be an early sign of enlarged prostate. Or it could just be a normal change due to aging. See your primary dr if you are concerned.

Not sure which "it": ...you're referring to. If "it" is "once in a while, I have trouble falling asleep after waking up..." the "it" is NOT a problem. Happens to almost everyone from time to time. If "it" is "have to urine in the middle of the night every night", then it's best to see a doctor. "It" can be a sign of prostate or kidney problems or diabetes. Meanwhile, it might help to also restrict salt intake.

Enlarged prostate: Early awakening can be caused by: depression,waking to void secondary to enlarged prostate, sleep apnea...among other causes. If the awakening is only occasional that would likely eliminate depression as the cause(unless you are feeling depressed). The likely cause is enlargement of the prostate(BPH). Try to eliminate liquids after 7pm. For more on BPH see>http://bit.ly/1fJa24j Speak with your DR