Severe magnesium deficiency, potentially from a strict ketogenic diet, can cause hypnagogic jerks, leading to insomnia and fear of falling asleep.

“I think I got so magnesium deficient from a strict keto diet and I had hypnagogic hypnagogic jerks which is when you're falling asleep and if anyone's experienced this they know this and you wake yourself up because you feel like you're falling and it's a magnesium deficiency primarily”