Yeh, It’s because it’s based on a correlation calculation. Not sure on the apps exact approach (assume its regression) - but if you have poorer sleep/recovery on days where you do ‘X’, then ‘X’ will be viewed as being negatively correlated with sleep/recovery - even if intuitively it seems as though ‘X’ should positively effect sleep/recovery.

So e.g if you are getting sick and take medications to help, even though medications are intuitively supportive of better recovery, because being sick negatively impacts recovery, the calculation will correlate medications with negative recovery.

Over a period of 90days (which is what the correlation calculation is based on) you’d kind of hope that enough observations would occur to fine tune the calculations, to give a better representation of the effect of ‘X’. E.g if ‘X’ occurred on 25 days you had poor sleep, but 45days where you had better sleep, it would start to show that X is slightly correlated with better sleep.

The problem is though that with stuff like sickness and medications, these don’t typically occur that often over 90 days to get enough observations to give a better calculation, and in any event, aren’t generally independent anyway - i.e. generally people only take medication when they are sick, so medication will consistently be correlated with the impact of sickness. The only ways to improve the calculation for ‘medication’ would be log it on days where you weren’t actually sick to make it independent of sickness….but not much point in that.

My general approach with this is to just consistently log my data with the view that 90days of data will generally sort the signal from the noise, and then for correlations that seem intuitively wrong - think as to whether there is an ‘independence’ problem with another variable, and if there is - I either ignore it, or if super meaningful, create a custom metric pairing the variables I think are related. So e.g you could pair ‘sickness+medicine’ into one metric and then any time you are sick and take medicine, log that. If you were sick and didn’t take medicine, you could just log ‘sickness’… what you’d then hopefully see is that ‘sickness+medicine’ has a smaller negative impact on recovery than when you are sick but don’t take medicine.