An electrically adjustable sun lounger comprising a frame and a reclining surface mounted onto the frame and meant for supporting a person, wherein the frame comprises lateral longitudinal elements, wherein the reclining surface comprises at least one head part, one central part and one foot part, wherein the foot part and the central part are pivotally connected to the central part at a foot-facing side thereof and at a head-facing side thereof, respectively, wherein the reclining surface is adjustable between a range of positions; which comprise at least a first position for a lying position of the person and a second position for a sitting position of the person, wherein the lounger is constructed in such manner that when passing from the first to the second position, the head part pivots relative to the central part in such manner that the angle (β) between the two parts on the upper side of the lounger is reduced whereas the foot part pivots relative to the central part in such manner that the angle (α) between the two parts on the bottom side of the lounger is reduced, wherein the frame is provided with a first, second and third rotation axis (A, B, C) which are arranged parallel to one another transversely to the longitudinal direction of the sun lounger, wherein the first rotation axis is connected to the foot part and the second rotation axis is connected to the central part and the third rotation axis is connected to the head part, and wherein the sun lounger comprises an electrically operable adjusting device for setting a desired position within said range, wherein the sun lounger comprises at least one solar module which is enabled for energy supply of a rechargeable electrical accumulator of the adjusting device, und wherein the sun lounger is constructed in a weatherproof manner, wherein the adjusting device is encapsulated against environmental influence, characterized in that, at least, also all of the existing bearings are encapsulated against environmental influence, wherein the adjusting device comprises an element being longitudinally adjustable between a retracted and an extended position and which is articulated, with its first end, to the frame, and, with its second end, to a part of the reclining surface, and wherein the adjustability of the reclining surface is provided by the following connections: - the foot part is articulated to a one-piece pivot member which is arranged pivotably around the first rotation axis of the frame, - the central part is provided with lateral longitudinal slots, in which the second rotation axis of the frame is received rotatably and pivotably, - the head part is arranged pivotably around the third rotation axis of the frame; and - the second end of the longitudinally adjustable element is connected to the head part via an angled pivot member. - the foot part is articulated to a one-piece pivot member which is arranged pivotably around the first rotation axis of the frame, - the central part is provided with lateral longitudinal slots, in which the second rotation axis of the frame is received rotatably and pivotably, - the head part is arranged pivotably around the third rotation axis of the frame; and - the second end of the longitudinally adjustable element is connected to the head part via an angled pivot member.