Not very bright at all. The process of becoming blinded by light is because the iris contracts when the light level increases. The reverse process of dilation is slow for humans, so the return to darkness leaves your eye with insufficient light coming in to see in the environment you suggest. This isn't a binary factor.
The VA calculates the rate of pursuit by dividing the number of credit hours being pursued by the number of credits considered to be full-time for the term. As as example, if the term is 10 to 13 weeks in length, 12 credits is considered full time. If the term is 8 weeks in length, 8 credits is considered full time.
Undergraduate, as stated, is often 12 semester credits or more. Half time should be at least 6 credits -- the minimum often needed to be eligible for financial aid. If you are in graduate school, half time is considered 5 or 6 credits, full time is at least 9 credit hours. (This pertains to schools in the US, at least state-run colleges and universities).