I noticed this: my heartrate spiked several days before a bad fever. I'd been traveling and not sleeping well for a few days, and my Fitbit HR monitor went up 1

I noticed this: my heartrate spiked several days before a bad fever. I'd been traveling and not sleeping well for a few days, and my Fitbit HR monitor went up 10-15 points. But it also could have been reporting that I was sleeping badly. Since bad sleep gives increased risk of catching a virus, it's important to know, but I'm not sure if it was detecting the virus or the sleep deprivation.