A recent study conducted by Rensselaer Polytechnic Institute (RPI) researchers and published in Genome Research provides an intriguing view into the fundamental mechanics of immune system function. This study supports the idea that optimal immune function may be tightly connected to a healthy circadian rhythm and the sleep-wake cycle.

According to the RPI researchers, circadian rhythms play a much greater part in the functioning of the immune system than was previously understood, specifically in the action of “killer cells” called macrophages, whose purpose is to find and kill invading organisms such as bacteria. More specifically, they discovered that the circadian rhythm controls killer cells.

Understanding Circadian Rhythms, Body Clocks

The human body is made up of an amazing collection of complex systems that work together as a unified whole. The unification of that whole, the synchronization of of those complex systems and their essential chemical reactions, relies on a system of biological clocks. These timing systems operate all the way down to the cellular level, with each individual cell having its own biological clock timing and controlling its functions. These clocks are supervised and synchronized by a group of about 20,000 neurons, called the suprachiasmatic nucleus (SCN), located in the hypothalamus.

These body clocks, having evolved over tens of thousands of years, are set to the most fundamental natural rhythm of all – the cycle of day and night. They operate on a roughly 24-hour schedule, a circadian rhythm. The body’s circadian rhythm governs a broad range of essential physical processes, such as hormone production and metabolism. Disruptions of the overall circadian rhythm, including disruptions to the tightly linked sleep-wake cycle, are associated with a heightened risk of an increasing number of diseases and chronic health conditions. Among these are obesity, cardiovascular disease, type 2 diabetes, Alzheimer’s disease and certain types of cancer, such as breast cancer.

The RPI researchers noted that the diseases typically linked to chronic disruptions of the circadian rhythm are also associated with inflammation, which is itself connected to the immune system. According to the researchers, because the circadian rhythm impacts immune system functioning on multiple levels, disruption of the circadian rhythm also leads to disruptions in immune function, setting the stage for the chronic inflammation that leads to a higher risk of developing diseases and chronic health conditions associated with inflammation.

How the Circadian Rhythm Controls Killer Cells

As explained by RPI assistant professor and lead study author Jennifer Hurley, the study focused on the relationship between the body clocks and the overarching circadian rhythm and the mechanical functioning of the immune system. They studied the killer cells – formally called macrophages – that do the work of seeking out and eliminating invading pathogens.

The study results showed that over a two day period, the RNA and protein levels in the macrophages were influenced by the circadian rhythm, but the influence of the circadian rhythm on the functioning of the macrophages didn’t stop there. The researchers found that the circadian rhythm also influenced metabolism regulation in a way that directly impacted immune function via energy production by the macrophages. Those changes in energy production served to control the timing of other critical immune system tasks and functions.

How to Promote Healthier Circadian Rhythm

As the body of evidence connecting the circadian rhythm to immune function and health continues to grow, the importance of a healthy circadian rhythm becomes more apparent. While genetics may hold some influence, there are plenty of other ways to promote a healthy circadian rhythm.

Light is one of the most important environmental cues for the circadian rhythm and among the easiest factors to control. Simply increasing your exposure to bright early morning light can help promote a healthier circadian rhythm. Boost that benefit by engaging in physical activity outside, in the morning light.

A regular schedule of sleeping, waking and eating is an important part of maintaining your circadian rhythm. To help you naturally stay on schedule, practice good sleep hygiene to help you fall asleep easier, improve sleep quality and wake up without an alarm clock. Try to allow yourself time for a 60-minute pre-sleep routine and eight hours of sleep. Avoid electronic devices and screens during that hour. Instead, create a relaxing routine, such as meditating or reading a book. Make your sleeping area as comfortable as possible, from room temperature to bedding to soft lighting. Don’t eat too much within a few hours of bedtime. Avoid alcohol and caffeine in the evening hours.

Simple Steps Can Yield Better Health

In light of the recent evidence that the circadian rhythm controls killer cells and influences other aspects of immune system function, it seems clear that working toward a healthier circadian rhythm is a critical part of protecting health and fighting disease. Fortunately, much of what you need to do to promote a healthier circadian rhythm is fairly simple and readily accessible to most people. A brisk walk in the morning sun, for example, doesn’t require any special or expensive equipment. Make gaining a more healthy control over your day-to-day schedule one of your priorities to achieve better overall health and well-being.