hi all,
I wanted to share a bit of data that might be informative for some as there isn’t much out there on differences and similarities between night and morning measurements
Below I show the two tools I use (camera measurement in HRV4Training in the morning) and Oura ring (night data). You can easily extrapolate to using another app / sensor for morning measurements, while it might be a bit harder to extrapolate to other ‘night HRV’ sensors, as many do not provide the average of the night (which is in my opinion the best way to use night data, see: What you need to know about Heart Rate Variability (HRV) data collected during the night | by Marco Altini | Medium )
Anyways, Since I started working with Oura, I’ve been looking more closely at morning vs night HRV data. See my last 30 days below. Great consistency in baseline changes for both heart rate and HRV between Oura’s night data and HRV4Training’s morning measurements 
I’ve tried to annotate the stressors, both positive and negative:
‣ a little extra alcohol intake around end of the year: affects night data more, as it is a “late stressor”
‣ consistent training, “high” volume and intensity, which typically lowers HR
‣ biofeedback 20 minutes per day. Possible effect on HRV
Morning and night measurements are both valid ways to capture changes in baseline physiological stress deriving from training and lifestyle stressors, as long as a few simple best practices are followed
Some more pointers are available here: https://twitter.com/altini_marco/status/1352914995001106432
I hope this helps
