I get two types of crashes. One, the classic: Do too much, feel lousy the rest of the day, and feel really really lousy about 20 hours after overexertion. A few days of 'intensive rest therapy' will see me recover to pre-crash level (which isn't flash but you take what you can get). Immensely frustrating but at least cause and effect are reasonably predictable. Two, the sneaky, creeping-up-on-you type: No identifiable cause, exertion levels firmly within energy envelope. Slow, almost imperceptible increase in symptoms over several days (weeks?). By the time I register the downhill slope the steamroller is unstoppable. Even with total rest symptoms keep getting worse for weeks. Then it takes several more weeks to make a partial recovery only, never quite back to pre-crash level (that's the most worrying bit). Anyone else get that second type of slow crash? Any theories on what's happening? Any ideas for preventing or stalling it? Some sort of very early warning symptom?