For an overnight "red-eye" flight in 2026, the window seat is almost universally considered the superior choice for sleep quality. The primary advantage is the solid wall to lean against; by using a travel pillow against the cabin wall, you can create a much more stable and comfortable sleeping position than you can in an aisle seat. Additionally, a window seat protects you from being "jostled" by passengers walking down the aisle or hit by the beverage cart during the night. Most importantly, in a window seat, you control the window shade, and you will not be woken up by your seatmates needing to get out to use the restroom. The aisle seat, while better for those with "restless leg syndrome" or a frequent need for the bathroom, is much harder to sleep in because you must remain alert to let others out. In 2026, unless you have a physical condition that requires frequent stretching, the "cocoon" effect of the window seat is the best way to ensure you arrive at your destination feeling rested and avoiding the "aisle seat neck snap."