B777 pilot reported a smoke alarm sounded and the crew diverted to a safe landing.

Narrative

I was approximately 1 hour into my scheduled break and was asleep in the Crew Bunk when I was awakened by the smoke alarm. I got dressed and coordinated with the FA to gain an understanding of the situation and assess the extent of the situation. After doing so I entered the cockpit to find the Captain and the FO in an emergency descent. They informed me we were diverting to ZZZ. I pulled up the approach chart; got the ATIS and tried to assist in the arrival. The Captain and the FO had already ran the appropriate checklist and made the decision to divert. They were doing a great job managing the descent and approach so I backed them up as best I could. Once we landed; I made the Remain Seated announcement and coordinated with the FAs in the back. We taxied to the gate and shut down the engines without further incident.