Body’s Biological Clock and Time of Day Affects Immune Cells, Mouse Study Shows

Body’s Biological Clock and Time of Day Affects Immune Cells, Mouse Study Shows

Researchers further explored how our internal biological clock — known as circadian rhythm — influences immune system responses. Disruptions to that rhythm are associated with immune diseases like multiple sclerosis (MS), although in ways not fully understood and, the study suggests, may affect response to treatment.

A natural 24-hour cycle that exists in every animal and plant, the circadian rhythm is known to regulate all physiological processes. Maintaining a healthy body clock is increasingly recognized as a key step for good health, and studies have shown that people with a disrupted internal clock — such as night-shift workers — have a higher incidence of diseases like MS.

Researchers at the Trinity Biomedical Sciences Institute, Dublin, and the Royal College of Surgeons Ireland (RCSI) used a mouse model of human MS — the experimental autoimmune encephalomyelitis (EAE) model – and showed that the time-of-day regulates the activation of several of the animals’ immune cells, .

Their study “Loss of the molecular clock in myeloid cells exacerbates T cell-mediated CNS autoimmune disease” was published in the journal Nature Communications.

They found that a gene called BMAL1 — a master regulator of the circadian clock — senses and acts in concert with the time of the day to suppress inflammation. Loss of BMAL1 or inducing EAE at midday (instead of midnight, for instance) was seen to lead to an enhanced inflammatory environment in the central nervous system and, subsequently, more severe disease progression in the mice.

“We found that the course of disease was significantly more severe in wild-type mice immunized at ZT6  … equating to middle of daylight hours, compared with mice immunized at ZT18,” or the equivalent of nighttime hours, the researchers wrote.

“In the year that the Nobel Prize in Medicine was awarded for discoveries on the molecular mechanisms controlling the circadian rhythm, our exciting findings suggest that our immune system is programmed to respond better to infection and insults encountered at different times in the 24-hour clock,” Kingston Mills, the study’s co-lead researcher and a professor of Experimental Immunology at Trinity, said in a press release.

“This has significant implications for the treatment of immune-mediated diseases and suggests there may be important differences in time of day response to drugs used to treat autoimmune diseases such as multiple sclerosis,” Mills added.

A better understanding of how to modulate the circadian rhythm and time-of-the-day cues may help design strategies that work to modulate the immune system.

“Collectively, our findings demonstrate that the myeloid molecular clock and circadian rhythms can influence the development of autoimmune disease. Bmal1 expression and a functional molecular clock in myeloid lineage cells appears to regulate these temporal variations, yielding a less pro-inflammatory environment overall,” the researchers concluded.

“Our data provide mechanistic insights into how time-of-day and clock disruption in myeloid cells impacts on autoimmunity thus providing opportunities to enhance circadian function or time-of-day drug-targeting strategies to alleviate autoimmune disease.”


  1. Astra says:

    I’m a night owl since I was born and always had trouble conforming to “normal” schedules, but had to; that’s the world we live in, after all. I also have MS. Very interesting finds!

  2. Joe Gendusa says:

    I find this article to be very true. I have SPMS and every night for seven days a week I feel better and can move better. I never could figure that out until now that I have read this.

  3. Billy says:

    I’m definitely in the owl family. Always have been since i can remember and i suspect always will be. To me, sleeping half the day and being up all night just doing normal routine things, this is normal. I dont think i trained myself into being this way its my natural default. None of this surprises me to hear. I personally believe there are other related traits a person can have or display which are directly related to this toipc. I always observed in myself that i have a natural dislike of being in even mild direct sunlight. I noticed it at work when i was a smoker, years ago, a small group of us would go outside together for our afternoon cigarette break and everyone else loved basking in the sun, i would retreat to the shadow of the building quick as i could. The sunlight to be feels irritating in some way like its itching my skin? The 2nd related point in vitamin D deficiencies. Obviously when sleeping patterns are basically reversed i tend to see more sunrises than anyone else alive but not many mornings. So i have always missed taking in good doses of the norning sunlight which is very different from afternoon sunlight. Morning is blue light, afternoon is red. Put simply, blue grows and nourishes, red ages and burns. Unless youre planning on flowering a pretty flower from the top of your head then the red light doesnt compare to the good value of morning sunlight for our bodies and particularly for vitamin D absorbtion. Also the morning light is what forces your internal rhythms into a proper schedule.

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