Is it normal that my third eye can only open at night time? When you're third eye opens, is it normal for other people to notice that your eyes are a different shade of your original? Can healthy drinks such as protein drinks improve spiritual awareness?
I'm not surprised that you are only able to open it at night time. I for one in my starting years, was only able to practice at night because for one there is way less distractions, and two it's easier to get into a meditative state from a tired and relaxed one. I have to ask though is there any opportunities during the day where you can relax? How about after a shower or bath and before you go dry off and leave take time to meditate and focus on opening your eye. PSI balls are a great easy practice to open the eye, they require no tools, and can be done quite fast. I would try and make one during the day and you just might notice it opening.
As for your eye color, I have no clue. There are some people with strange genetics where eye color is changed either from body temperature, emotions, or something else. It's rare but you could have it. It could be because the meditative states required to open your eye puts your body in a different enough state that linked to this eye trait, they change color.
For your third inquiry, all things related to magic work the best when you're healthy. If you lack protein which is apart of keeping you healthy, then protein shakes may help in the effectiveness of gathering energy and accomplishing spells. As for spiritual awareness, what do you mean by that? Aware of other spirits? Awareness of entities and yourself is apart of magic and your third eye. I'm pretty sure drinking a protein shake isn't gonna make all the spirits around you easy to notice, but like I already mentioned a healthier you leads to a healthier practice.
