Can lutein or zeaxanthin cause side effects such as insomnia, tiredness, dizziness, or constiipation? I want to take it to improve my vision.

No, however... Lutein and Zeaxanthin are carotenoids naturally found in fruits and vegetables and do not have any side effects, but they may be in capsules that have additives or preservatives some may react to, so I advise companies like Pure Encapsulations and Thorne that don't use those. Many other nutrients are good for eyes such as Vit. A, C, D, E, zinc, selenium and EFA's. See