Signals

Heart rate variability (HRV)

The variation in time between heartbeats, measured in milliseconds (rMSSD). Higher HRV = better-regulated autonomic nervous system. Wellex reports your nightly HRV (the most stable measure) and a 7-day rolling baseline.

Resting heart rate (RHR)

Your average heart rate during the deepest part of sleep. RHR is one of the slowest-moving and most reliable indicators of fitness and recovery. A 3–5 bpm increase often signals incoming illness 24–48 hours before symptoms.

Sleep stages

Wellex segments the night into awake, light, deep and REM. Deep sleep is when physical recovery happens; REM is when memory consolidation happens. Both matter.

Skin temperature

Wellex tracks the deviation from your personal baseline, not the absolute number. A 0.4°C overnight increase is the early signal for fever, ovulation or alcohol metabolism.

GSR (galvanic skin response)

Reflects sympathetic nervous system activation. Used to model stress balance, not absolute stress.

Blood oxygen (SpO₂)

Spot-measured during sleep. Used to detect chronic desaturation patterns; not a clinical-grade reading.

Steps

Daily step count tracked continuously. Wellex uses steps as a standalone WVI metric (7% weight). The protective threshold starts at 5,000 steps per day (Lancet 2025), with maximum benefit at 12,500+. Below 3,000 steps triggers a hard cap on your WVI score.

Active Calories

Calories burned from movement and training, excluding basal metabolic rate (BMR). Wellex tracks active calories separately from total calories to measure genuine physical effort. The target for a Good score is 500+ kcal of active calories per day.

Activity Load (ACWR)

The Acute:Chronic Workload Ratio compares your recent training load (7 days) against your longer-term average (28 days) using an exponentially weighted moving average. The sweet spot is 0.8 to 1.3. Below 0.6 signals detraining; above 1.5 signals overtraining and elevated injury risk (Gabbett 2016).