Do you have bats in your attic? It is a common problem since bats love finding dark undisturbed shelter where they can stay during daylight hours. Just like any other pests that invade your home, bats carry with them many problems, most seriously so, dangers to your health.
Bat droppings can pile up in your attic if you have them living there, and that could be spreading disease. While bats usually will run away, they could hurt you if cornered, and often there will be a wild flight if there are several bats living in the attic and you disturb them.
A solution that can prove to be very effective against bats is to install a one-way excursion device over the opening they are using to enter your attic. This will only allow them to leave the attic but not come back in again. For it to work, however, it is important that any other holes and cracks that the bats could use to gain entry are patched up.