Air mattress

An air mattress comprising:

• an air cell unit including an air cell;
• and
• a controller that controls the internal pressure of the air cell, the controller configured to perform:
• a first operation to cause the internal pressure of the air cell to increase up to a second value if the controller determines that the internal pressure of the air cell satisfies a second condition after a first condition corresponding to a person's getting off of the air cell unit has been satisfied, and
• a second operation to increase the internal pressure of the air cell if the controller has determined the internal pressure of the air cell has satisfied a third condition after the first operation, wherein
• the first condition is a decrease of the internal pressure of the air cell, which is from a first value to the second value, being greater than a first threshold value and a rate of the decrease being greater than a first threshold,
• the second condition is a further decrease of the internal pressure of the air cell, which is from the second value to a third value, being greater than a second threshold value,
• the third condition is an increase of the internal pressure of the air cell, which is from the second value to a fourth value, being greater than a third threshold value, and
• the second operation increases the internal pressure of the air cell to the first value or a fifth value that is greater than the first value.