Night "seizures" that aren't seizures

My partner has suffered from tonic-clonic seizures since childhood. He is now in his mid-30s. His epilepsy is controlled with medication (Tegretol). At night he has what seem like seizures (limbs seize up, body stiffens, he convulses/jerks) but he has told me this is a side effect of his medication and they don't show up as seizures when his brain activity is mapped overnight. These typically happen at least once a night, although he's had four+ episodes in one evenings. He's aware of them and believes they are more frequent after eating salty meals. I'm worried about this. In terms of his quality of life, he's not sleeping through the night, which makes him even more tired/ drowsy than he would be just on the Tegretol alone. Given I sleep right next to him, i've been inadvertently hit (sometimes quite hard) in the face/neck/chest. This worries me. Has anyone ever heard of this? Please help me.