I notice that the Fitbit sense SPO2 works only night and >3 hour sleep. That is useless to me if the SPO2 failed to get reading are you going to ask me to go to bed for at lease 3 hours to test it? We pay so much for such product but with a white elephant SPO2 feature. Can this be upgrade to real time? Huawel cost me only UD 25 SPO2 is real time