A low profile armrest articulation mechanism for a passenger seat is disclosed. The passenger seat has a seatback reclinable from an upright configuration to a berthed or horizontal configuration (e.g., parallel to the seatpan). The mechanism includes moving stops connecting the armrests on either side to the seatback and linkages connecting the moving stops to the seat frame. As the seatback reclines, the moving stops maintain the armrests at an optimally ergonomic angle (e.g., substantially parallel to the seatpan) for as long as possible. When the seatback reaches the fully reclined or berthed configuration, the armrests may be pivoted upward into a berthed orientation flush with the seatback, adding bed space to the berthed configuration.