Might be worth seeing a sleep consultant/going to a sleep clinic to get an assessment.
There are all sorts of sleep conditions/parasomnias/behaviours etc that have all kinds of causes and treatments.
Could be caused by/linked to trauma, neurological conditions, sleep apnoea (where the periods of not breathing can fragment your sleep, leaving you in between sleep states, and this can give rise to parasomnia behaviours cropping up)
Hard to know based on what you’ve written, but worth getting checked out if it’s causing you/your partner problems (especially physical harm)
In the past (before I got my parasomnias more under control) I’ve kicked my partner, punched her in the face (thankfully, not hard enough to cause any injury but it was certainly a shock and upsetting for both of us), I’ve leapt on her, and grabbed her. Usually completely unaware that I’ve done it until she’s either woken me up or told me the next day
I went to a sleep clinic, was diagnosed with non-REM parasomnias. My therapist believes it’s connected to trauma/PTSD. The sleep dr thinks it’s neurological. As far as I’m concerned, it be either/neither/both and, for me, the cause doesn’t really matter as much as effective treatment because it was having so much impact.
I was prescribed melatonin (I’m in the UK where you can’t just go and buy melatonin - it has to be prescribed) and it has massively helped manage the parasomnias and reduce the number and intensity of occurrences.
As others have said, if I am in a stage where I’m having more frequent night terrors etc, we tend to sleep separately until things have settled.
Anxiety/stress can also cause disturbed sleep/bad dreams/a jacked up nervous system etc. So, relaxation before bed (watching an easy going comedy show, having a soothing bath, doing a few minutes of deep breathing exercises) may all help to ease things and lead to a calmer night.
But also may not!