Hmmm...OK, so imagine the scene...
Captain has been in his/her bunk for several hours and is well into REM sleep in boobo-bye-byes land. Suddenly the 'plane flies through the mount Etna ash cloud and all four engines flame out (it has happened).
So he/she is woken, struggles to put trousers and shoes back on and tries to wake up. Gets to cockpit and, wiping the sleep from their eyes, takes control of the situation....yeah right.
OR; somebody decides to invade the cockpit with either a suicide bid, or a desire to 'have a go', locking the cockpit door behind them....
Of course I'm jealous, but really; is it right that hours should be claimed while asleep outside the cockpit ?