A control method includes the steps of: (a) monitoring an electrooculogram signal of a user using an electrooculogram sensor for monitoring the electrooculogram signal of the user (b) determining whether or not a sleep state of the user is a non-rapid eye movement (non-REM) sleep state, based on the electrooculogram signal monitored in step (a) and (c) performing a control operation to cause an element capable of warming the eye area of the user to warm an eye area of the user when the sleep state of the user is determined not to be the non-REM sleep state in step (b).
