But—if I understand correctly, you did not take any melatonin between nights in which you randomized—have you looked “treatment effect vs. length of time since last experimental night”? This would be a very crude way of getting at tolerance effects.
Good idea! Had a brief look now: I filtered my data for the 40 days on which I took melatonin, then for each one calculated the time (in days) since I last took melatonin (so not the last day I ran the experiment, but the last day I ran the expeirment where I was in one of the two intervention groups), and looked for a correlation between number of days since previous melatonin intake and time to fall asleep. There’s maybe a tiny hint that there could be tolerance effects at play, but the data is insufficient for anything conclusive:
The point on the very right is the first day where I took melatonin—for that one, the “day since last intake” is not really defined, so I just choose the maximum distance between days I had + 1.
We do find a very slightly negative correlation which seems to indicate that after taking a break from the experiment (or having had some control group days recently) made the melatonin slightly more effective at reducing time to fall asleep, but then again, a [-0.4, 0.22] CI doesn’t tell us much. :)
(Update: I also made a small linear regression and obtained the formula predicted_time_to_fall_asleep = 27.1 − 0.24 * days_since_last_intake (for days on which I took melatonin) - but, again, large error bars around that coefficient)
I have a (completed) 5-year melatonin self-experiment that I will hopefully write up later this year (although… I have been saying that for 12+ months at this point), will be fun to compare notes.
Good idea! Had a brief look now: I filtered my data for the 40 days on which I took melatonin, then for each one calculated the time (in days) since I last took melatonin (so not the last day I ran the experiment, but the last day I ran the expeirment where I was in one of the two intervention groups), and looked for a correlation between number of days since previous melatonin intake and time to fall asleep. There’s maybe a tiny hint that there could be tolerance effects at play, but the data is insufficient for anything conclusive:
The point on the very right is the first day where I took melatonin—for that one, the “day since last intake” is not really defined, so I just choose the maximum distance between days I had + 1.
We do find a very slightly negative correlation which seems to indicate that after taking a break from the experiment (or having had some control group days recently) made the melatonin slightly more effective at reducing time to fall asleep, but then again, a [-0.4, 0.22] CI doesn’t tell us much. :)
(Update: I also made a small linear regression and obtained the formula predicted_time_to_fall_asleep = 27.1 − 0.24 * days_since_last_intake (for days on which I took melatonin) - but, again, large error bars around that coefficient)
Oh wow, please do!