Usually, people's vision at night is weaker than that in the day. It is normal because the ability to the light at night is not that sensitive like that at the day. You could increase the Vitamin A to make the vision at night improve to some degree. It really works. You could try it.
Many people experience poorer night vision, and so do me. First of all, biologically, human have a poor night vision than many other animals, because night vision is made of two approaches combination, sufficient spectral range and sufficient tapetum lucidum. Human lacks the tapetum lucidum, so normally we have a not so good vision in night. I am not sure how poor your night vision is. If it is a very serious problem, which impacts your daily life, then it might be sending some indication to require for your attention. As to the underlying root, it ranges from bright sunlight exposure to chronic disease. Finding out the root is imperative to get proper treatment. Sunlight exposure might weaken night vision ability up to two days, which sounds creepy but it is true. The bright light could impair your night vision, so if you need to go to beach to enjoy sunshine, you must wear sunglasses to protect your eyes. Vitamin or zinc deficiency might lead to night vision problem too. It is rare but possible. Have more carrots, yellow or green leafy vegetables (for vitamin A), beef, beans and nuts (for zinc), which have sufficient nutrition of vitamin A and zinc. The first symptom of cataracts is poor night vision. The vision is blurred and distorted so that you might see halos around light. People with diabetes have a higher risk to get eye conditions. High blood sugar might damages blood vessels and nerve ends, which contribute to bad night vision. If you just had your Lasik surgery, the bad night vision is one of the common side effects it might bring to you temporarily. After you got completely healed in 3-6months, it will disappear in most cases. Just visit your ophthalmologist, he or she can give you the guidance and proper treatment.
I think there must be something bad happened to your eye health, because as you can see, poor night vision is a health risk sign you know? Which indicates your health problem. Anyway, generally speaking, poor night vision is resulted from a lack of some vitamins such as B, E or A. And in the mean time, maybe you have got myopia, or other eye disease, so what you should do is to do something to stop your problem from getting worse and consult an eye doctor for some professional advice.