A sleep aiding device and a method thereof, a server and a method thereof and a sleep aiding system. The sleep aiding device includes: a physical-sign detecting part, configured to detect physical sign data associated with a user; a brainwave detecting part, configured to detect brainwave signal data associated with the user; and a display and play part, configured to: receive a display and play instruction, and adjust at least one of a display mode and a play mode of the sleep aiding device according to the display and play instruction. The display and play instruction is generated according to at least one of the physical sign data and the brainwave signal data.