It is difficult to answer as each person's body clock varies. Some people need to sleep for 8hrs or more, others cope just fine with 4 hours. It depends on *your* sleep pattern.

If you can cope with waking that early everyday and sleep later on, then you should go ahead. But maybe you should try this pattern for a few days before making a commitment. So you'd know if you can sustain the rythm for an extended period...