I'm not sure about the refreshing part but the guilt does build up for me. In fact, I can't nap at all so I just lie there trying to rest and exactly the opposite happens - I start getting thoughts of how I should be doing my work and how I could go about it. I try to resist thinking and ideas come up. Eventually, I get too restless and can't help but get up and work. I have noticed the same thing happen when I used to meditate.