AYO should be used with open eyes. We have designed AYO and AYO's light diffusion system in a way that it is very gentle and usually does not distract the user in any way - so the user can continue most of his/her daily routine seamlessly (e.g. working on the laptop, reading a book, cooking, etc.)
Using AYO with closed eyes will practically have no effect whatsoever since the human eyelids usually block more than 95% of the light, minimizing the effect of AYO.
AYO's light and AYO's light diffusion system in general has been carefully tested and is fully certified for photobiological safety by the world renowned independent certification body TUV. You can read more on the effect of blue light in this article.