On 08.08.2014, aircraft B777-300-ER Registration VT-JEL belonging to M/s Jet Airways was involved in loss of altitude incident during cruise over Turkish Airspace. The PIC was undergoing controlled rest as per the DGCA operations circular 8/2013 and the controls were with the First Officer. The PIC woke up to see that the aircraft had lost assigned altitude and was climbing through FL 320. The investigation was carried under Rule 13(1) Page 2 of 10 of, The Aircraft (Investigation of Accidents and Incidents) Rule 2012. The cause of incident was inadvertently carrying out level change while updating the heading in altitude window.