Mark,
You gave a fairly accurate description of me. I will be 53 in May. I have 'sorta' joked with my wife about the onset of Alzheimers. She insists that is not it. I find that lack of sleep makes it worse - like if I only get 5 1/2 hours - which happens more than I care to admit. Exercise makes it better as does abstaining from alcohol - which I do less than I care to admit. I struggle with names more than I used to. On the flip side (or woodshop side), when I am birding, I can concentrate for hours and the time slides by without notice. So...Drink less, Sleep More and take the time for down time. I heard an interesting program on PBS Sunday about the need for sleep. Over the past 50 years, the average amount of time spent sleeping has decreased significantly, almost 2 hours according to the program.
