2Sa 5:4-5 KJV David was thirty years old when he began to reign, and he reigned forty years. [v. 5] In Hebron he reigned over Judah seven years and six months: and in Jerusalem he reigned thirty and three years over all Israel and Judah. This would have made David 37 when he became king of all Israel. Do not get confused between 'Judah' and 'Israel': they are not the same.
Sleep paralysis: A frightening form of paralysis that occurs when a person suddenly finds himself or herself unable to move for a few minutes, most often upon falling asleep or waking up. Sleep paralysis is due to an irregularity in passing between the stages of sleep and wakefulness.
Although there may be certain triggers, ultimately sleep paralysis is believed to be a problem with the regulation of REM. During this phase of sleep, the body is kept relaxed so that dreams are not acted out. If this relaxation, or atonia, occurs while the person is awake, it can cause temporary paralysis. This may be experienced when a REM period is disrupted.