[mikem170]

I googled and found the correct term for what bothered my friend: Sleep Paralysis [0]:

> Sleep paralysis is a condition identified by a brief loss of muscle control, known as atonia , that happens just after falling asleep or waking up. In addition to atonia, people often experience hallucinations during episodes of sleep paralysis.

I didn't get as far as knowing if there are mitigations. I saw where it can happen falling asleep and waking up, so maybe it is relevant.

[0] https://www.sleepfoundation.org/parasomnias/sleep-paralysis