Stress, as it happens.

What the score means

• Calm 0–25
• Mild 26–50
• Elevated 51–75
• High 76–100

Sitting calm and awake reads about 20; deep sleep reads about 2. A heart rate 8 beats a minute above your calm with 30 % less variability reads 60, Elevated. 20 beats above with half the variability reads 93, High.

Stress says what your heart is doing, not why. Anything that raises your heart rate or lowers your HRV while you sit still reads the same way: a tense meeting, caffeine, a warm room, a big meal, alcohol or illness.

Still or moving

Keely reads every 5-minute window that has heart rate, whatever you’re doing, and every number counts it: now, the timeline, time in levels, the averages and moments. What you’re doing only picks the method. A window is Active when:

• any minute in it has more than 10 steps, or the Loop rates it as more than light activity;
• it overlaps a workout;
• your heart rate is at or above your Zone 1 floor, which catches rides and lifting that barely move the wrist.

After activity, a window is settling while your heart rate is more than 15 beats a minute above resting: for up to 30 minutes after a workout, and up to 10 minutes after a walk.

Active and settling windows are read from your heart rate alone, as body stress, between your calm and your maximum:

C           = resting HR + calm
Body stress = 20 + 80 × (HR − C) ÷ (max HR − C)

Calm and awake reads 20 on both scales, and your maximum heart rate reads 100. With a resting heart rate of 51 and a maximum of 185, a walk at 95 beats a minute reads 41 (Mild), the Zone 1 floor at 118 reads 56 (Elevated), and a threshold run at 165 reads 87 (High).

On the timeline it’s one line. Scrub a stretch where you moved and it says “from heart rate”, and the time in levels card shows how much of the day was read this way, with its peak. Behind the line, only your workouts from Training are marked.

How the score is computed

While you’re still, both signals are compared with a calm and awake reference built on your nightly baselines. Everyone starts at their resting heart rate plus 12 beats a minute, and about 78 % of their nightly HRV. Then Keely learns your own: from the still, awake windows of your last 14 days, it moves toward where you actually sit when calm, a little at a time and within bounds (8 to 16 beats a minute above resting).

zHR    = (HR − (resting HR + calm)) ÷ 8
zRMSSD = (ln RMSSD − (ln nightly HRV − calm HRV)) ÷ 0.35
s      = 0.9 × zHR − 0.9 × zRMSSD
Stress = 100 ÷ (1 + e^−(s − 1.4))

Without enough clean beats for RMSSD, heart rate carries the reading alone: s = 1.2 × zHR.

Until you have 3 nights, Keely uses your profile’s resting heart rate (or 60) and an HRV of 45 ms, and treats the reading as provisional.

Live and stored

• Live. With your Loop connected and Keely open, heart rate and beat intervals stream from the band, and the score covers the last five minutes once they hold two minutes of heart rate. The same rule picks the method: a minute where the Loop flags at least half its beats for movement or lost contact counts as moving, and the reading comes from heart rate alone.
• Stored. The rest of the time, Keely scores the Loop’s 24/7 data when it syncs, and labels the reading with its time, such as “As of 11:20”. Gaps stay gaps.

Moments

A moment is when stress stood out: at least two windows in a row (10 minutes) above 50 during the day, or above 30 at night, still or moving. Moments show on the timeline, day and night. One that’s mostly moving is named by the workout under it, or Active, until you tag it.

Frequently asked questions

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