In recent years, we've heard a lot about sleep as an important factor in our performance. Until I saw the article I refer to here, everything I've seen related to quantity and quality of sleep.
Several years ago, as Chief Pilot for a small air freight company, I used to substitute for pilots when they were unavailable for their scheduled flight. This could mean anything from an all-night run to a mid-morning flight. Naturally, my sleep schedule varied greatly.
Comparing that time to now, I'm quite sure my mood is more settled now when I sleep on a very consistent schedule.
Here's Inc. magazine's Bill Murphy Jr. discussing a study which indicates that consistency of sleep schedule is important to effective rest. To the surprise of many, this study says you can't “make up” for missing sleep with more sleep hours! I guess you could say, “Lost sleep is never found!”
For anyone who works “Swing shifts” – a different shift every week – it may be impossible to avoid this. That's not as common now in the information age as it was a few years ago. If you're one of the few so affected, you might want to encourage your employer to reconsider that policy.
I haven't done a lot of research on this thought. However, this issue is likely just “jet lag”. If you've traveled across multiple time zones you're no doubt familiar with that. For many, it results in serious disorientation for up to a week after arriving in a new time zone.
So, you may want to consider sleeping more regularly if your schedule is different on different days.