Circadian rhythm in layman’s terms means all the hormones and body functions that happen in a 24 hour period. From hormones that cause you to be sleepy at night to nervous system activity that causes bowel movements, your body is on a schedule. That schedule is something that all living things have based on their species and needs, but this internal clock has a close relationship with the day/night cycle of light, too. Having said that, we know that our bodies do certain things at certain times and when it comes to hormone release and immune function, that could mean that taking certain medications or vaccinations at certain times increases effectiveness.

Did you know that there have been studies showing those who received flu vaccines in the morning had higher levels of anti-flu antibodies than those that received them later in the day? This suggests that the WHEN someone gets a vaccine may determine it’s effectiveness. We won’t go into whether or not someone should even get a vaccine in the first place, but it”s worth gaining this data about timing.

The most common indication of circadian rhythm is cortisol release. Cortisol is inversely related to melatonin, which means as melatonin rises, your cortisol goes down. Melatonin makes you sleepy, but cortisol wakes you up. So, it makes sense that cortisol should be the highest in the morning. Cortisol also suppresses inflammation and regulates certain immune responses. What if we could time those immune responses to manipulate an outcome? It may make certain treatments safer and more effective.

Cholesterol medications:
Research has suggested that the enzyme that regulates cholesterol production in rats is most active at night. This may mean that taking a drug like a statin may be most effective if taken at night. While this is interesting and really helpful if you have a reason to take a statin, I would love to point out that statins are one of the most easily-avoidable drugs out there with appropriate lifestyle changes!

Chemotherapy:
Genes that determine cell division are rhythmic which means that chemo that targets cells actively replicating (think reproductive tissue and intestinal lining) can be timed to limit healthy cell death. ‘Over the past 30 years, experimental models and clinical trials have found that timing chemo regimens can significantly affect their toxicty and effectiveness.” ( The scientist Magazine)

Anti-histamines:
These allergy drugs are found to be most effective when taken at night or early in the morning. We also now know that they cause cognitive issues and brain shrinkage, so lets entertain finding the ROOT causes of allergies vs treating the symptoms!

Blood Pressure Medication:
It’s no secret that heart attacks happen more frequently during certain times of the day. Don’t believe me? Ask a cardiologist. If you take an angiotensin-2 receptor blocker for blood pressure, it is most effective at controlling blood pressure if taken at night.

I’m all about fixing the problem versus treating the symptom, but pay attention because I promise this will be a tweak in medication recommendations as time goes on. Don’t want to wait until they figure all that out? Then I encourage you to fix the reason you would need to take meds in the first place. ;)