Yes... but I wonder if it's the quality of sleep, or the quality of the wake, sometimes, that's at issue? How we sleep depends on a lot of hormonal and quasi-hormonal stuff (signalling molecules like adenosine that regulate sleepiness/wakefulness), these being out of wack both during the sleeping and wakefulness period could make people feel crummy during the day, and sleep poorly at night--each feeding into the other, affecting the other, but the main cause of both being the circadian dysrhythm. The "no blue light at night" has its related therapy of the light box with lots of blue light, in the morning vs. SAD. These people don't just get the right cues for sleep, they get the right cues for wakefulness.