FWIW, I had a bunch of issues that I found out that were directly related to my sleep patterns. My doctor did a sleep test not once, but twice over the last 10 years. One of these was done before I starting riding my bike and the other was done about 4 years ago while I had cranked up the mileage.
It was found that I had severe sleep apnea. This made total sense since my BP was up and I was waking up many times during the night. They found I was stopping breathing more than 30 times a hour. This constant up and down with my heart never let it sufficiently rest and hence I was always tired mid afternoon and could use a nap.
This resulted in a CPAP. First try sucked and I did not use it. After the second test, I made myself do it and now after 3+ years of 100% useage I sleep really well. My average is almost 8 hours a night. My incidents have went from over 30 to now just one per hour. Note, the average person stops breathing about 3 times an hour so I am better than that.
The other issue with this is that after riding the bike these years, the amount of air pressure that is required to keep my airway open was cut in half from that first test to what I am at now. So, the biking helped greatly.
Now, I do also suffer a bit of the old male syndrome of having to get up etc. My urologist said if it goes to more than 2 a night he will look at it more seriously. I usually get up once and many nights, like last night I make it thru the night.
The HBP is another issue that I have and that has not gone away even with cycling and the cpap. I am under meds for that, but it is under control. I was hoping to get off the meds with increased cycling, but that has not happened. I think that problem is more being driven by my weight but it is incredibly difficult to drop weight even riding 100+ miles a week with low T. Yes, I have that too. Typical old age male syndrome.
So, if you are not sleeping well even after a big workout and you are 45+, you should definitely look into a sleep study. I think in the long run, my sleep studies have saved my life. My father also had severe apnea and never did anything about it and was constantly falling asleep during the day. If you snore, you have some degree of apnea.
Waking up a lot during the night "could" be a sign that your brain is not getting enough oxygen and it calls down to the heart to start pumping more blood and that is when you wake up. So, it is two fold.
As I said for me, I sleep really well now. I have gotten used to the machine and it is now (sadly) a part of my life but I have learned to live with it. The alternative is not waking up from one of my episodes.
Message is, pay attention to your symptoms, they usually mean something. Falling asleep is one thing, staying asleep is another and getting up 3 or more times a night to use the bathroom is yet another. It sucks getting old, but the key is learning to live with all the changes which are all symptoms of getting older. If you are really tired mid afternoon and could fall asleep like after lunch, this is another indicator you might have a sleeping disorder.
john