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Understanding Time Discrepancies Between the Session Timer and Graphs

It is a common observation for users to notice that the main session timer in the Inner Balance (or emWave) app progresses faster than the data plotted on the HRV and Coherence graphs. For example, your main session clock may read 1 minute and 5 seconds, while your HRV graph only shows 45 seconds of data, and the Coherence graph has only just started plotting.

This difference in timing is an expected design behavior of the software and is not indicative of data loss, dropped signals, or a glitch.

Here is a breakdown of the specific mechanisms that cause these graphs to progress at different rates, particularly at the beginning of a session:

1. The Main Session Length (Clock Time)

The main session timer acts as a simple stopwatch. It begins counting the moment you start the session (00:00) and progresses continuously in real-time. It tracks total elapsed clock time, regardless of what the biological sensors are processing.

2. The HRV Graph (Stabilization & Cleaning)

Unlike the main timer, the HRV (Heart Rate Variability) graph does not plot simple clock time; it plots valid, filtered physiological data.

  • Stabilization Period: When a session begins, the sensor requires a brief stabilization period to lock onto your pulse and establish a clean baseline.

  • Artifact Removal: The software actively filters out initial movement artifacts (such as adjusting the ear clip). Because the app is actively cleaning the data, the plotted HRV line will naturally lag slightly behind the main clock. The time shown on the HRV graph represents the actual amount of clean, usable heartbeat data collected.

3. The Coherence Over Time Graph (The Rolling Window)

The mechanism causing the most noticeable delay—often appearing 30 seconds or more into a session—is the mathematical formula used to calculate Coherence.

  • Coherence cannot be calculated from a single heartbeat. It is a measure of the rhythm and variation of your heartbeats over a span of time.

  • To generate a single Coherence score, the HeartMath algorithm requires a rolling time window of accumulated HRV data (typically 30 to 64 seconds) to perform a complex calculation called a Fast Fourier Transform (FFT).

  • Therefore, the Coherence Over Time graph physically cannot plot any points during the first ~30 seconds of your session. It must wait in the background while the HRV graph collects enough data to complete that first time window. Once that first block of data is collected, the graph will appear and begin plotting continuously.

Summary

The discrepancies you see at the beginning and end of your sessions are intentional. The Main Length tracks total elapsed time, the HRV graph tracks processed physiological data (minus the stabilization period), and the Coherence graph requires a rolling 30-second block of that HRV data before it can begin plotting.