I almost returned my Garmin Venu 2 since I could not find a way to record naps. However, after discovering that I can add notes to daily sleep-page I decided on a compromise. I am going to approximately measure my nap-time using the Garmin's stop-watch and make note of it on the sleep-page. If I am adamant to record it as a part of the sleep-diagram, I can manually change the wake up time on that diagram to to reflect the overall nap-time. I understand that this is not the best or an elegant solution, but considering Garmin's deaf ear on this issue I think it serves the purpose with a bit of work.