In collaboration with the organizers of the 18th Congress of the European Biological Rhythms Society (EBRS) (taking place in Lübeck in Northern Germany from the 24th to 28th of August 2025), three congress speakers are interviewed to talk about their research. As the first spotlight, Prof. Michael Hastings (MRC Laboratory of Molecular Biology, Cambridge) talks about his research journey from circatidal rhythms in marine organisms to circadian and circaannual rhythms in mammals. Our main focus is on the neurochemistry within the central clock of the suprachiasmatic nucleus (SCN) enabling it to tell time. We discuss the most relevant factors that support the SCN in telling time, and what means the SCN has to synchronize other clocks within our body. With respect to melatonin, we discuss its role in sleep versus informing our body about the current season. We also talk about supplementing melatonin for specific populations. Lastly, Michael shares memories from attending previous EBRS congresses and why you should consider joining it this year.

EBRS homepage: https://ebrs-online.org/index.php/events/ebrs2025.html

Chapters:

(0:00:39) Introducing the EBRS 2025 spotlights

(0:03:51) Michael Hastings

(0:07:17) Circatidal rhythms

(0:14:38) The central clock / SCN

(0:24:47) Different zeitgebers

(0:35:17) Melatonin

(0:46:14) Melatonin as a sleeping aid?

(0:51:38) EBRS congress experience

(0:58:22) Michael’s career advice

(1:10:02) Funny anecdote

(1:13:54) Outro

Studies that Michael refers to:

Reviews on circatidal rhythms

https://doi.org/10.1016/j.cub.2008.06.041

https://doi.org/10.1016/j.tig.2024.01.006

Prevalence of mutations in clock genes to make the period length shorter or longer than approx. 24 hours, rare familial sleep disorders

https://doi.org/10.1038/s41386-019-0476-7

Mice mutations support that the same enzymes are involved as in the human sleep disorders

https://www.nature.com/articles/s41583-018-0026-z

Period genes in the SCN are activated by light

https://doi.org/10.1016/S0092-8674(00)80494-8

Caffeine can phase shift the circadian clock

https://doi.org/10.1126/scitranslmed.aac5125

Manipulation of NPY and serotonin can shift the SCN clock

https://doi.org/10.1152/ajpregu.00320.2022

Human cortisol levels increase before awakening in anticipation of wake

https://doi.org/10.1677/JOE-07-0378

Temperature in the physiological range can act as a zeitgeber to entrain peripheral clocks

https://doi.org/10.1016/S0960-9822(02)01145-4

When interfering with neuropeptide levels within the SCN, you can entrain the SCN with temperature cycles

https://doi.org/10.1126/science.1195262

High levels of estradiol make the SCN run faster

https://doi.org/10.1126/science.557840

Melatonin is a transplacental zeitgeber

https://pubmed.ncbi.nlm.nih.gov/3780553/

https://doi.org/10.1177/074873049701200603

Martha Gillette and others applied melatonin to brain slides containing the SCN, showing that this could shift the SCN clock, the sensitivity of the SCN to this melatonin effect was found to occur during daytime (when melatonin is not released naturally)

https://link.springer.com/article/10.1007/s00441-002-0576-1

GWAS papers: variance of melatonin receptor are related to the type 2 diabetes andmetabolic disorders

https://www.nature.com/articles/ng.277

https://www.nature.com/articles/s41574-018-0130-1

Contacting Michael Hastings:

Homepage: https://www2.mrc-lmb.cam.ac.uk/group-leaders/h-to-m/michael-hastings/

Email: ⁠mha@mrc-lmb.cam.ac.uk⁠