Yes, your astigmatism will cause you to see halos around light because of the not adjustment of lights of objects at the right position in the pupils. Your prescription may be higher because of the tiredness which you need to pay attention to. You could use the eye drops to release the symptom.
No, astigmatism shouldn't cause halos. Also it can't cause dimming, brightness or any changes to the outward appearance of the eye. What's more, astigmatism only can change your eyesight over years but it can't be changes in the ability to see and make out detail in a sudden If you find you can see halos, you may have got other problems such as glaucoma, cataracts, diabetic retinopathy and conjunctivitis. You should go the see the doctor as soon as possible.
Halos refer to the light ring/circle around the light source which impacts the night vision. It is more noticeable in a dark circumstances. The possible reasons triggered halo vision include cataracts, intraocular surgery or common vision problems like myopia, hyperopia and astigmatism. I have myopia and astigmatism too. I especially hate to drive at night. The halos and glares from light sources bother me a lot. As to halo vision caused by intradocular surgery, it is a temporary symptom, which could disappear after the wound healed. If it is caused by cataract, you need to treat your cataract through medication or surgery procedure. If the halos are caused by the vision problem, you can consider to fix the vision problem, myopia and astigmatism. Now it seems possible to coat the lenses of glasses with anti-glare coating to reduce the halos and glares.