system
A chat on subreddit /r/NoStupidQuestions
human
I’m not sure about how nursing schools teach in the UK but I assume it’s along the same lines as the US.  At least back in the 90’s when I was in school, we were taught to never wake up anyone by touching their upper body.  Rotation through the VA was the main reason. Veterans who may or may not have PTSD react strongly to being awakened by touching. And you’re more away from someone who may lunge up from sleep swinging their fists.  Also it’s less frightening to the patient to not wake up to someone “standing over you”. 

I’d still (as a nurse) try to remember to wake you like you’d asked. But it is deep ingrained in nursing school to grab your foot.
gpt
They teach you in nursing school to tickle people?

I'm almost certain they don't.