An aircraft comprising a sleep system, the sleep system comprising: a seat (210, 304, 306) configured to move between an upright position and a reclined position and including a first headrest; and a lateral sleep apparatus positioned adjacent the seat, the lateral sleep apparatus including: a second headrest; and a cradle coupled to the second headrest, the cradle including a first attachment assembly and a second attachment assembly, the first attachment assembly to couple the cradle to a support structure (410, 1302) of a cabin of the aircraft and the second attachment assembly to couple the cradle to the seat, wherein the first attachment assembly is to enable movement of the second headrest between a first lateral position and a second lateral position different than the first lateral position when the seat moves between the upright position and the reclined position, wherein the first attachment assembly includes a track and a slider, wherein the track is to couple to the support structure and the slider is attached to the cradle, the track is to slidably receive the slider to enable the cradle to move relative to the support structure between a first end of the track and a second end of the track opposite the first end when the seat moves between the upright position and the reclined position, wherein the second attachment assembly is to maintain an elevation of the second headrest relative the first headrest when the seat moves between the upright position and the reclined position. a seat (210, 304, 306) configured to move between an upright position and a reclined position and including a first headrest; and a lateral sleep apparatus positioned adjacent the seat, the lateral sleep apparatus including: a second headrest; and a cradle coupled to the second headrest, the cradle including a first attachment assembly and a second attachment assembly, the first attachment assembly to couple the cradle to a support structure (410, 1302) of a cabin of the aircraft and the second attachment assembly to couple the cradle to the seat, wherein the first attachment assembly is to enable movement of the second headrest between a first lateral position and a second lateral position different than the first lateral position when the seat moves between the upright position and the reclined position, wherein the first attachment assembly includes a track and a slider, wherein the track is to couple to the support structure and the slider is attached to the cradle, the track is to slidably receive the slider to enable the cradle to move relative to the support structure between a first end of the track and a second end of the track opposite the first end when the seat moves between the upright position and the reclined position, wherein the second attachment assembly is to maintain an elevation of the second headrest relative the first headrest when the seat moves between the upright position and the reclined position. a second headrest; and a cradle coupled to the second headrest, the cradle including a first attachment assembly and a second attachment assembly, the first attachment assembly to couple the cradle to a support structure (410, 1302) of a cabin of the aircraft and the second attachment assembly to couple the cradle to the seat, wherein the first attachment assembly is to enable movement of the second headrest between a first lateral position and a second lateral position different than the first lateral position when the seat moves between the upright position and the reclined position, wherein the first attachment assembly includes a track and a slider, wherein the track is to couple to the support structure and the slider is attached to the cradle, the track is to slidably receive the slider to enable the cradle to move relative to the support structure between a first end of the track and a second end of the track opposite the first end when the seat moves between the upright position and the reclined position, wherein the second attachment assembly is to maintain an elevation of the second headrest relative the first headrest when the seat moves between the upright position and the reclined position.