Sleep isn't an exact science, so don't expect an exact answer. Some people can live on 6 hours of sleep and be fully alert. Some people need 9. Personally, I fluctuate.
I keep notebooks on subjects I'm learning and use journals to reflect on my overall progress. This self-assessment helps me to not only retain what I learn, but to give me a pulse on my progress: am I in a slow month or am I on fire?
Also, intelligence, is an ephemeral quality. It's really hard to measure due to its elusive nature and the manner in which it manifests differently in people. Perhaps return to some early work or problems you used to enjoy and see if you can still solve them or find new insights in them. That might at least give you some actualization.
Journaling and keeping records of my work habits has been one of the best ways for me to judge my own performance. The amazing thing is, you scarcely have to go back and reread them, just the process of writing down your performance for a given day helps you to mentally assess yourself.
That's an interesting one. Do you think it helps spot not only declines in processing speed or memory but also any potential loss in the "magic spark" part of intelligence where you make breakthroughs/have great ideas? I'm most worried that if I lost that I wouldn't notice...
It helps make you more consistent. The self-awareness it takes to honestly assess yourself and be interested in your own improvement helps you to address your own weaknesses. Over time you'll find that you'll have periods of high mental activity and low periods, but over time as you begin to record them and alter your strategies that they will even out into a pretty consistent cycle.
Personally, I don't think that the "magic spark" is something I can train for or seek to attain. It's a random event IMO, and will only lead to disappointment if I stake my entire life's work on waiting for it to happen. I'm not a person who enjoys uncertainties if I can avoid them.
Sleep isn't an exact science, so don't expect an exact answer. Some people can live on 6 hours of sleep and be fully alert. Some people need 9. Personally, I fluctuate.
I keep notebooks on subjects I'm learning and use journals to reflect on my overall progress. This self-assessment helps me to not only retain what I learn, but to give me a pulse on my progress: am I in a slow month or am I on fire?
Also, intelligence, is an ephemeral quality. It's really hard to measure due to its elusive nature and the manner in which it manifests differently in people. Perhaps return to some early work or problems you used to enjoy and see if you can still solve them or find new insights in them. That might at least give you some actualization.