I have many of my feeds set to refresh at 3-hour intervals. I figured this would be often enough during the day and would always trigger a refresh in the morning, when the system was asleep for more than 3 hours. But instead I'm often not getting any new articles in the morning – they only come in a few hours later, from several different feeds (so very likely not related to websites publishing at a specific time of day).

I tried putting the system to sleep about 30 minutes before the prefs window said an update was due, then waited an hour before waking again. Curiously, I next saw this:

This would then continue to count down (i.e. the minute portion increased), but sometimes switched to a more sane "24 minutes" or so (and then back to minus years again). In the end it seemed to actually refresh very roughly half an hour after waking, and only then stopped showing the weird negative time. I'm suspecting the timers pause during sleep or otherwise get confused, causing them to trigger not in absolute time but in system awake time... or maybe something else is going on.