My Husband Woke In The Night Freezing Cold And Shaking

my husband woke in the night freezing cold and shaking he felt like ice! it wasn't a cold night! i had to quickly dress him in socks sweater and beanie and hold him to try and warm him up. it was a nice evening i wore a cotton nightgown it wasn't too hot or cold ! he said he felt cold to the bone he felt icy cold too ! any idea as to what would cause this
many thanks