Why is it always 'dark' when I astral project or lucid dream?

Not physically; it could be in the middle of the day while I'm taking a nap, but my lucid dream or AP will always take place in the 'dark' or in some night-time type setting. This used to frighten me, but now it just frustrates me because I keep wanting it to be bright and luminous but it just stays dark. Is this because I'm not getting enough sunlight so my subconscious just replays darkness? I think I used to be able to 'see' better in my lucid dreams and APs, but the last couple years it's just dark and depressing - kinda like walking through your house with maybe a candle; that level of visibility. Please help me if you can; I have some other problems with AP as well; for instance, when I'm becoming conscious I experience an intense pressure/pain in my head while I'm trying to 'disconnect' from my sleep-paralyzed body. Please answer here if you can or feel free to email me personally decreebass at gmail dot com if you have experience with this. Thanks everybody!