Both lower and upper berths on AC-2 Tier coaches have an excellent LED reading light (similar to that found in aircraft) - see photo. This makes it great for nighttime reading without disturbing others. It's a vast improvement over the 'shutter' lamps found on the non-LHB coaches which function better as room heaters!
The LHB coaches also seem to be a little more square in lateral cross section permitting more room on the upper berth as the photo shows.