The nighty average value and trend remains very helpful. A rested body shows higher averages than a stressed body.
Normally you see a lower HRV value in the evening and a higher HRV value in the morning - resulting from nighty recover. This is not always the case though and sometimes misleading. Emfit therefore also shows a 2nd indicator “Integrated Recovery”:
Integrated Recovery is the area remaining under the RMSSD graph, and in some sense it indicates how much recovery you gain during the whole night. For example, some people may start to recover very nicely (RMSSD graph shooting upwards) during early hours of the night, after they go to bed and fall asleep, but towards the morning hours they may start become anxious (for example because of work stress), and their RMSSD starts to decline. As a result, morning RMSSD may be quite low when compared to evening RMSSD, thus indicating poor recovery, even though during the night there has been some good recovery. This is where integrated recovery steps in, as it indicates also this good recovery earlier in the night.
Integrated Recovery and Total Recovery should be checked together; even if Total Recovery is low, but Integrated Recovery is medium or high with regard to ones own history, then there has been some recovery. On the other hand, if they both are low, then recovery is propably not sufficient, and one should avoid stressing him/herself too much, for example, avoid very heavy physical exercise.
Total Recovery as difference between morning and evening HRV values:
Recovery is simply difference between morning and evening RMSSD values. Usually it should be positive, indicating that there has been efficient recovery and resting during the night. Of course, this should be analyzed with regard to activities of previous day: if previous day was very light (no stress, no heavy exercise) and evening RMSSD is relatively high, it is not reasonable to expect high Recovery number, because there is no load to recover from.
Values of Recovery are highly individual, and you should inspect them against your own baseline values, and also in comparison to Evening RMSSD values.
Emfit takes an average of an unknown period in the evening and morning to define the Evening HRV values and Morning HRV values. In my posted chart you the evening value to be well above 30 while the first reading is just above 20.