Hard for me to detect effects.
Overall, I didn't notice any difference in my sleep, either in terms of quality, ease of falling asleep, or restedness and energy levels the next day. No negatives either — it seems any effects were too subtle for me to pick up on over 5 days.
I am generally pretty satisfied with my 'sleep hygiene' to begin with, so it's possible someone starting from a less desirable baseline might be better served. The one issue I do experience is the occasional night where I can't fall asleep at my regular time. Most nights, no problem, but every once in a while it'll take me longer, sometimes by several hours. I did experience this once during the trial, but had regular sleep the other 4 nights.