Lipitor is a brand name for the medication atorvastatin, which is used to lower cholesterol levels in the blood. According to the NHS [2], atorvastatin is usually taken once a day, with or without food. The exact dosage and frequency of use will depend on the individual's condition and response to the medication, and it is important to follow the instructions given by the doctor or pharmacist.

It is also important to note that taking Lipitor at night may be more effective for some people. According to Drugs.com [3], taking atorvastatin at night may help lower cholesterol levels more effectively than taking it during the day. This is because the body produces more cholesterol at night, and taking the medication at this time can help block the production of cholesterol more effectively. However, it is important to consult with a doctor or pharmacist before changing the time of day that the medication is taken.

In summary, Lipitor (atorvastatin) is typically taken once a day, with or without food, as prescribed by a doctor or pharmacist. Taking the medication at night may be more effective for some people, but it is important to consult with a healthcare professional before making any changes to the medication regimen.

Sources:
[2] https://www.nhs.uk/medicines/atorvastatin/how-and-when-to-take-atorvastatin/
[3] https://www.drugs.com/medical-answers/does-lipitor-work-better-if-you-take-it-at-night-416127/