About This Answer
A meditator says that with eyes closed it feels as though the lights are on, and that sometimes she sits for an hour without knowing it. Ajahn Dtun replies that not knowing is not good; there must be mindfulness, or one may simply have dozed off.
The light itself is fine if one is mindfully aware of it. It is just a condition that arises and passes away, a little calm of mind, but it does not yet make the defilements less. What really matters is giving up greed, anger and suffering. So keep establishing mindfulness in meditation, even up to the moment of falling asleep.