tuck someone in 
phrasal verb with tuck verb [ T usually + adv/prep ] uk/tʌk/ us/tʌk/
  (UK also tuck someone up)      
 给(孩子)掖好被子;将(孩子)在床上安顿好
to make someone comfortable in bed, especially a child, by arranging the covers around them
  Daddy, if I go to bed now will you tuck me in? 爸爸,要是我现在去睡觉你会帮我掖被子吗? 
 The children are safely tucked up in bed. 孩子们安逸地躺在被子里。