Hi Catherine, have you seen this article? it revealed dysbiosis due to diet disrupts the equilibrium between microbes and circadian rhythms that affects host metabolic functions resulting in obesity  (http://www.ncbi.nlm.nih.gov/pubmed/25891358) (http://www.ncbi.nlm.nih.gov/pubmed/26628099)

I hope it gives you some idea 

Dear Catherine,

Many thanks. You are asking some wonderful, intelligent and very interesting questions. Only if I could answer them. Regardless I am following your questions and trying to learn more about such important-generally unnoticed-rhythms of life and universe.

I have also come across this following article if it is any use

Message in a Biota: Gut Microbes Signal to the Circadian Clock

Cell Host & Microbe, Volume 17, Issue 5, 13 May 2015, Pages 541–543

Emily V. Marcinkevicius, Mimi M. Shirasu-Hiza

best wishes,

Refik

Thanks Catherine,

Keep posting and I will be following this unorthodox and not so main stream field. The natural rhythms been there mostly since the begiining of life, so not surprising that they are connected to life itself and our physical and psychological exsitance. I think this field of research is finally blooming, also because there is alot of public interest now:-) Very important!

best wishes,

Refik

Hi,

A recent review that RG actually just suggested to me:

Chronobiomics: The Biological Clock as a New Principle in Host–Microbial Interactions

October 2015 · PLoS Pathogens 10/2015; 11(10):e1005113. DOI:10.1371/journal.ppat.1005113

Best,

David

Dear Catherine,

Thank you for sharing the paper "Bacteria need “sleep” too?: Microbiome circadian rhythmicity, metabolic disease, and beyond" by Mark Trinder · Jordan Bisanz · Jeremy Paul Burton · Gregor Reid. 

What I would really like to know is if you have come across similar research studies in birds as well. 

Host circadian melatonin is likely to modulate the microbiome, however, the levels of melatonin synthesis in gut cells (mostly enterochromaffin cells) is far higher than that of the host pineal circadian rhythm. Likely that there is variability in the levels of melatonin synthesis by different gut bacteria, although this has still to be shown in published data. As to whether bacterial circadian rhythms show variations in melatonin or indeed in melatonin's ratio with its precursor, N-acetylserotonin (NAS) is unknown. This may be of some importance, as NAS is a BDNF mimic at its receptor, TrKB. BDNF is a known trophic factor in many cancers, including colorectal cancers. As such, the NAS/melatonin ratio, which can be significantly increased by ATP, is likely to be important in the gut bacteria-host interaction. Melatonin production by bacteria, as well as host gut cells, will be important to determine. However, variations in the NAS/melatonin ratio may prove of more importance. I have added a recent publication on the NAS/melatonin ratio in glioblastoma, which may be of some interest.