We have had our cat for 4 years now, and since he was 2 or 3, he has had violent twitches in his sleep. When he has his sleep fits, he often twitches, his eyes open a bit, and sometimes he makes a noise, that I can only describe as screaming. I just realized how violent they are sometimes, since he is between my legs when he just had an fit. The fits don't wake him up, and he seems perfectly fine like nothing happened if I wake him up. I saw that cats with seizures have the same fit. But I always read that sleep apnea could look like seizures. How do I tell if he is having sleep apnea, or a seizure? This only occurs when he's sleeping, so I originally thought they were nightmares due to his screaming. Sometimes if I wake him up (when he gets really bad), he will hiss as soon as he wakes up, and then calms down and licks me...so could it possible be nightmares too?