Michael Pollan quit caffeine for 3 months. He says that your relation to caffeine becomes clear when you come off it. He said that he felt a veil between him and reality when he was not having caffeine. Essentially, we have "... caffeinated consciousness".

Oddly, the strong adenosinergic pressure from ~20 hours wake combined from caffeine withdrawal didn't lead to increased SWS. Indeed, there was a nonsignificant trend towards a decrease in SWS. One possibility is that caffeine induced SWS surplus accumulation over the previous week, reducing SWS drive. However, this could alternatively be explained by the 60 minute nap.

Withdrawal restored REM sleep under these conditions. The withdrawal condition looks quite similar to placebo (both REM and SWS), which is rather surprising.