You track your steps, your sleep, your money. But not the body running all of it.

Resting heart rate was measured twice, about 10 years apart, in 29,325 adults in Norway without known heart disease, who were then followed for about 12 more years. A rise from under 70 to over 85: hazard ratio 1.9 (95% CI 1.0–3.6) for death from ischemic heart disease; a rise from 70–85 to over 85: 1.8 (1.2–2.8). A long-term association, not an early warning from one morning scan.

A meta-analysis of 46 studies with 1,246,203 adults from the general population. Every 10 bpm higher resting heart rate went with a relative risk of 1.09 (95% CI 1.07–1.12) for death from any cause and 1.08 (1.06–1.10) for cardiovascular death. Compared with the lowest group, over 80 bpm: 1.45 (1.34–1.57) for death from any cause. Observational studies that differed from one another; an association, not proof that lowering your heart rate changes your risk.

A meta-analysis of 8 studies with 21,988 people without known cardiovascular disease. Lowest versus highest HRV (SDNN): relative risk 1.35 (95% CI 1.10–1.67) for a first fatal or non-fatal cardiovascular event; across HRV measures, a 32–45% higher risk. HRV was measured from ECG recordings, not a camera scan, and moonScan does not assess cardiovascular risk.

Nearly 33 million days of resting heart rate from 92,457 adults wearing a wrist tracker. Individual averages ranged from 40 to 109 bpm, while each person's own values stayed much more consistent. An observational study; whether spotting departures improves care still needs research.

Overnight heart recordings from 4,098 Finnish employees, comparing each person's nights with and without alcohol. Alcohol raised heart rate and lowered HRV in the first hours of sleep, more with more drinks and even at low amounts. An HRV-based recovery measure fell by 9, 24 and 39 percentage points after low, moderate and high intake. Measured with a chest recorder during sleep, not a morning camera scan.

A review of 37 studies on psychological stress and HRV. In most of them HRV changed under stress, most often as lower parasympathetic (rest-and-digest) activity. Mostly short lab and field studies; not a stress test for one person.

A review of 191 controlled exercise studies in healthy people. Every type of exercise lowered resting heart rate on average; endurance training and yoga lowered it significantly in both women and men. Group averages from training programmes; how much your own rate changes varies.

237 women in Switzerland wore a wrist sensor in bed for up to a year. Resting heart rate and breathing rate shifted significantly between cycle phases, and HRV varied too. Measured overnight with a wrist device, not a camera scan; moonScan does not tell you your cycle phase.

Wrist-tracker data from 2,745 people with a PCR-confirmed COVID-19 infection. Breathing rate and heart rate were typically higher during illness, and HRV lower. The study did not test a camera scan, and moonScan does not detect illness.

Smartwatch data from 32 people with COVID-19, out of about 5,300 participants. In 26 of them heart rate, steps or sleep changed; in 22 of the 25 with known symptom dates, the change showed up before or on the day symptoms began. A small smartwatch study; moonScan does not detect illness.