When to take meds is rarely included with prescriptions. The drug labels tell you how many times a day to swallow them and occasionally advise you to take some with meals. However, our bodies have clocks that synchronize with sleep/wakefulness cycles. For instance, statins that lower our cholesterol work by inhibiting the liver from making it. Our livers make the most cholesterol as we sleep; therefore, statins are most effective when taken after the evening meal until bedtime. Cholesterol is necessary but not in excess; it is the foundational molecule to make a number of hormones, especially adrenal steroids and sex hormones. However, it is almost impossible, even with the most powerful statins, to lower cholesterol to a level that interferes with hormone production.
Next, especially with once a day meds, there is a drug concept that is important—drug absorption curve. Low dose aspirin is glazed with a retardant to keep it from dissolving in the stomach and causing erosions, which can bleed. Such are labeled enteric-coated or safety-coated. Enteric-coated, low-dose tablets are the recommended aspirins to take for wellbeing. Their primary function is to prevent heart attacks, among other benefits, by partly disrupting the clotting mechanism. The optimal time to achieve the highest level of aspirin in the morning is to take aspirin at night. Taking coated aspirin at night makes sense because the greatest numbers of heart attacks and the most serious ones occur in the morning hours.
Medicines for high blood pressure consistently have better results when taken at bedtime rather than in the morning. In one study, patients were followed for over five years on the same blood pressure meds with one group taking the meds in the morning and the other at night. The nighttime group had vascular deaths and major vascular events such as heart attacks and strokes that were one-third of the morning group.
People having arthritis pain should note when they have the worst episodes and time their NSAIDS pain meds four to six hours before. Usually, this means the arthritis meds should be taken in the mornings.
As mentioned, medicines that are taken once a day are termed extended-release (ER). Many meds are available in ER form. Usually, that is the more desirable form because their absorption and reduction are slower than meds that must be taken more often. Taken less often, they should be taken more regularly. I asked my doctor to arrange my meds so that I take them all once a day. ER meds concentration is lowest just after being taken. As a group ER meds should be taken at night because metabolism and a lot of risks decrease as we sleep.