Daily Morning HRV Measurement with Chest Strap
Jamieson has used morning HRV measurements for over 20 years, beginning with full EKG-lead Russian systems. He distinguishes this from overnight wearables (Oura, Apple Watch) that average HRV across sleep and are heavily swayed by late-night activities. In his view, the morning protocol is analogous to weighing yourself fasted rather than multiple times throughout the day — it yields a cleaner, more honest signal. He also stresses data integrity: athletes sometimes resist or don’t comply, making the data useless, but for motivated individuals this is the gold standard.
In the supine, rested state, short-term RMSSD primarily reflects vagal (parasympathetic) modulation of the sinoatrial node. Because it is measured at the same circadian point daily, it minimizes the confounding influence of food, movement, and recent stress, isolating the overnight recovery’s net effect.
Jamieson uses this method daily and built the Morpheus system around it, noting that his morning averages rose as he increased his aerobic base.
The biggest advantage to [morning measurement] is we can see where you are at the end of that sleep recovery cycle because the way I approach this is each day is its own stress recovery cycle. … I want to see where I’m at in the morning and what that process looks like at the end of it so I can make informed decisions.

