Lipitor, which contains atorvastatin, is a medication used to lower cholesterol levels in the body [1]. According to the Mayo Clinic [2], some common side effects of Lipitor include headache, diarrhea, joint pain, and muscle pain. However, both the Mayo Clinic and AARP [3] note that Lipitor can cause insomnia or other sleep disturbances as a less common side effect. It is important to speak with a healthcare provider if you experience any side effects while taking Lipitor.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.mayoclinic.org/drugs-supplements/atorvastatin-oral-route/side-effects/drg-20067003
[3] https://www.aarp.org/health/drugs-supplements/info-04-2013/medications-that-can-cause-insomnia.html