For my melatonin experiment, number of awakenings was 2.86 vs 2.43, but the p-value was only 0.43. The problem is that the standard deviation is 2.25! (On many nights, I awaken zero or one times, but on one particularly bad night, I woke up 7 times.) I suspect more data would show a more reliable effect and maybe a greater effect size than d=0.19.
For my melatonin experiment, number of awakenings was 2.86 vs 2.43, but the p-value was only 0.43. The problem is that the standard deviation is 2.25! (On many nights, I awaken zero or one times, but on one particularly bad night, I woke up 7 times.) I suspect more data would show a more reliable effect and maybe a greater effect size than d=0.19.
To expand; if d<=0.19, to detect this effect at p<0.05 with 75% odds, we need ~75 pairs of nights or ~150 nights of data:
Doable, but not trivial.