Can the Garmin CIRQA be worn on the upper arm?

Yes. The CIRQA officially supports wrist and upper arm wear, with the position set per activity in Garmin Connect. A dedicated upper arm band is available at $59.99 in black, in both S/M and L/XL.

Does upper arm wear improve heart rate accuracy on the CIRQA?

For high-intensity exercise, yes. Wrist movement during vigorous effort creates motion artefact that degrades optical heart rate readings. The upper arm sits over the bicep on a flatter, more stable surface with less movement, which produces cleaner data during intervals, threshold runs, and contact sports.

Does the CIRQA track sleep when worn on the upper arm?

Garmin does not specify upper arm wear as the recommended position for sleep tracking. Skin temperature is measured during sleep and the wrist is the natural default for most wearers overnight. Upper arm wear is better suited to specific exercise use cases.