@newtoni48 Most of the modern appliances/wearables are controlled by, and linked to, the accompanying phone via a health app via Bluetooth or equivalent. I know that Apple has one, and there must be third party ones, as there are for the Android with which I am most familiar (Samsung 'Health' and its adjunct heart assessment app for blood pressure and ECG).

In the case of Health, it also monitors sleep processes and stages, and I'm quite certain Apple's does as well. My point is that you can get a good look at your overall current state by looking at HRV and AHR (heart rate variability and average heart rate while sleeping). Next morning, upon waking, you can open the phone's apps and take a look at SPO2 (saturation of haemoglobin with O2). average HR, the heart's average for variability (it should lie somewhere within a global optimal range, somewhere near 42ms), and the breakdown of each of the stages of sleep and how long you spent in them comparatively. A quick glance at the app, maybe 30 seconds in all, will give the wearer a good indication of overall health.

Even going further, the 'waking pulse rate' of the heart, taken without moving much and when still in bed, and by enabling the heart monitor function on your wristwatch, will reveal if you should probably back off of intended hard physical work that day, and maybe the next as well. Most people can calculate a running average for waking pulse. When you get a raised result, say 60 BPM instead of your usual average rate of 53 BPM while asleep, that might be a sign that you need more rest, more sleep, or that you're fighting a pathogen of some kind, even that you have underlying inflammation or obvious pain. It's a cheap, handy, and highly effective way to assess one's heart health and its readiness to take on the obligations of the day.