What one man learned from obsessively tracking his vital signs for 48 years – Vox.

Robert Sothern is the ultimate quantified man. For 48 years, five or six times each day, he’s been tracking his bodily functions and mental acuity in extensive — almost absurd — detail.

“I measure my heart rate for a minute,” he tells me on a recent phone call. “I measure blood pressure. I measure respiration for two minutes, breathing slowly and counting how many times I inhale. I measure peak flow [air flow from the lungs], and I’m doing time estimation [counting to 60 without looking at the clock, and then seeing if it matches].” Fourteen years ago, he started to wear a step tracker.

The former chronobiologist at the University of Minnesota still rarely misses a day, and at 69 years old he says he’ll continue making measurements for the foreseeable future.

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Some insights, over time our internal circadian clock appears to break down. “We are rhythmic creatures” – optimizing, sticking-to and having routines that change over time to compensative for our-slowing-down clocks will be valuable.