Yes, that's my point. You can read this either way. But we do know that sleep deprivation is harmful, and it's conceivable that this might point to a mechanism

Yes, that's my point. You can read this either way. But we do know that sleep deprivation is harmful, and it's conceivable that this might point to a mechanism by which that harm is caused. Or it might be a defence mechanism which the caffeine is now interfering with, making things worse.