Well, that's a good question; I'm not enough of a sleep expert to know, but it's possible the 2 hours of sleep could stave off the effects of insomnia for some time or they might actually stave them off for a full 24 hours more. A standard sleep cycle is roughly 90 minutes long, and there's some evidence to indicate that the raw amount of sleep in hours isn't actually that important for the purposes of restoring the brain's ability to function properly; some data indicates that the grogginess we feel when waking up sometimes has more to do with our sleep being interrupted during a sleep cycle as opposed to at the end of one. So, theoretically, it's possible a sleep-deprived person might feel quite refreshed after just two hours of sleep. But again, I'm no expert.