system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why is it fairly easy to keep track of how much time has passed while awake, but a short nap of even 5-10 minutes can make it feel like hours have passed?
gpt
While awake you’re able to pick up on things like the brightness coming in from the outside and are participating in tasks that you’re likely familiar with and can anticipate the duration. Probably more importantly, you likely have a computer, wall clock, or cell phone showing you the time, whether you’re deliberately checking it or not. 

When you sleep, if you’re not a regular napper, you will probably assume you’ve been asleep for the normal amount of time, since you’ve been unconscious to the queues that normally help you track time. This is especially true if you did not decide to fall asleep and wake up to darkness with nothing to tell you what time it may be.