I have used the chest strap while running for better results than ohr. Can I wear a chest strap while sleeping, to get better hr results, aand with teh right chest strap, hrv?
Some straps like HRM Pro would be capable of recording and storing heart rate without an activity and syncing results directly to Connect Mobile. They don't have sleep or HRV analysis however, so I agree that a strap is not a solution.
But fortunately optical heart rate (including just rate variability) is most reliable during sleep when there's very little wrist movement, so a strap wouldn't probably change that much.