set an alarm to wake yourself up a little before the average time you might have this happen. keep a regular sleep schedule, avoid onerogenic drugs like nicotene and caffine,, look over what drugs you could be taking in or foods of certain sorts and change them too; maybe you are not eating enough or too much before bed? it isnt important to find the cause nessicarily as it is to find a way to jostle you out of this habit. adjusting sleep time and waking up during the night right before these happen using an alarm clock would be my cheif recomendation.