I don't see any other way? When you sleep (suspend to RAM), everything is stored in RAM and is encrypted but the master key is present in kernel memory (if I recall correctly).
However, if you hibernate (suspend to disk) the entire contents of RAM (including the master key) is written/encrypted to disk and the RAM is cleared.
When you wake the machine up you have to re-enter the passphrase to decrypt the master key to re-load disk contents back to memory.
However, if you hibernate (suspend to disk) the entire contents of RAM (including the master key) is written/encrypted to disk and the RAM is cleared.
When you wake the machine up you have to re-enter the passphrase to decrypt the master key to re-load disk contents back to memory.