The thing at the end of my bed

At one time I loved to tuck my top sheet in at the end of my bed and felt secure, but then I experienced something evilly scary.
I felt something (a hand?) come up from the end of the bed and grab my foot.
Now before you think I'm completely bonkers, I know that didn't really happen, and believe me that is what helps me sleep at night. 

I was going to sleep and must have dreamed it just as I dozed off. I have dreamed I was falling before right after sleeping, which made me wake up and my body experienced an involuntary jump.

Even though I know it can't be real--I refuse to sleep with the sheet tucked in and my feet must be free to move around or to move out of bed quickly.
It's a silly fear, but still a fear.
SIL-5

Monster under the bed