It seems that we notice changes around our decade birthdays. For many, eyes change around the age of forty. I know mine did; I had finally tried contact lenses with the prescription that I had used for several years. It was a short experiment because I found that I had trouble reading with them. You see, my eyes had alterred enough to require bifocals. A decade later, at fifty, give or take, I noticed my energy levels dropping. As a teacher, I'd sit at my desk in the evenings to mark papers or plan lessons, and it would be a slog.
Now that I am in my early sixties, I can report that another change is occurring and has been for several years now. Sleep. Or lack of it.
While I've often had trouble falling asleep, I usually hadn't had much difficulty in staying asleep. But in the past few years that has shifted. Depending on the night, I might go to bed at midnight, and I might even fall asleep soon after on some nights. But I now seem to be waking up fairly early (for me, in my historical context). I might awaken anywhere from about 5:30 to 7:30 in the morning but most likely about halfway between those two extremes. If I had fallen asleep around midnight, that's usually close to enough sleep for me — but only close and not quite enough. However, if my sleep gets truncated at both ends, say 1:30 to 5:30, it's not good. I require more sleep than that. But what I require and what I get can be very different. It can be quite frustrating.
At an almost identical age, getting enough sleep is also Cuppa's problem, but in her case it isn't lack of sleep. As her body changes, she requires more and more slumber. She seems to need and usually obtain about ten hours, and even then, she might feel completely drained by supper time. If she must remain perky in the evening for some reason, she will drink coffee in copious quantities and still fall blissfully asleep and remain that way for many, many blissful hours.
Oddly enough, she has typically been the more energetic person in this couple with more stamina than me. Yet here we are — with opposite sides of the same vexing problem. Neither of us can get enough sleep.
So, beware younguns; changes await. Unless you are of a very different constitution, I am almost willing to wager that you will notice at least some changes in the very areas that I have mentioned.