A Rest action is an action the player may undertake during the Investigator Phase. It allows them to spend one of their actions to recover 1 point of Health and 1 point of Sanity.
Some items, like the Fresh Fruit, trigger during a Rest Action. Many negative Conditions allow the player to roll a check or a die roll in order to remove the condition before a Reckoning event can trigger them during a rest action. The player may attempt to remove as many conditions as he likes during a rest action.
A player may not use a Rest Action if he shares a space with a monster.