Aside from being a great song, I'm a constant sufferer. It also seems like a great excuse to not do some work.
"Oh, I'm pretty tired. I'm not going to absorb anything so I might as well watch some television and go to bed."
The problem here is that you end up staying up late watching your program and the cycle continues. By the time you've realised where you are, it is way too late to make anything up in the way of progress.
When I had scripts to learn I would read a little every day, at varying points of the day and in varying states, drunk, exhausted, well fed, rested, whatever. Sometimes it would feel like I'd made no progress and other times it felt easy. However, what became apparent is that on show night I would never have issues, regardless of how strung out I was from overwork or sleep deprivation.
This is a key method I offer to everyone. It's really unlikely that you'll be in the perfect zone for information absorption every day, especially if you have commitments outside of study and general well being (employment, partners and social lives just to name a few).
You will get tired, sick, run down, angry, sad and hungry. But I you know how to access your brain when you're not in peak form, imagine what you're capable of when you are?
Another side effect of this kind of working method is that different states prompt different styles of thought. I write more creatively when I smoke. I write better music under the influence. I'm really pleasant when I'm hungover and I'm the best audience when I'm sleep deprived.
There is always a point too far, but before that spot is reached, it's a valuable experience to see what works for you when - and what doesn't.
Off to cook, read and nap.