Described are adjustable seats having a lower portion of a back rest attached to a seat frame having an upper frame and a lower frame. A pivot axis is positioned at an upper end of the lower portion of the back rest, and an upper portion of the back rest is pivotally attached to the pivot axis. The location of the pivot axis is configured to be positioned below a person's shoulders when the person is seated in the adjustable seat. The upper portion of the back rest is also pivotally adjustable relative to the lower portion of the back rest. A seat pan having a front portion pivotally coupled to a rear portion can be attached to the upper frame. An actuation mechanism is configured to simultaneously control a vertical height of the upper frame and a rotational position of the front portion of the seat pan.