Rome, 29 October 2025
Dear Editor,
we were glad to see the article “The prevalence and estimated burden of somatoform
disorders: a systematic review and meta-analysis of their epidemiology” by Siig, et al.,
published on Lancet Psychiatry in October 2025, as an indicator of greater attention towards
somatoform disorders, which are often underestimated both in frequency and in severity, and not
well understood in terms of biological mechanisms.
Collecting longitudinal clinical observations in our practice we got recently interested in
Guilbert’s Syndrome. It is well known that this Syndrome is characterized metabolically
by an excess of unconjugated bilirubin due to a genetic disorder, that affects both bilirubin
metabolism and the metabolism of a few drugs as well, increasing their toxicity (1). Albeit
only a few pathological outcomes have been recorded in scientific studies (2), at clinical
level a number of annoying symptoms are complained by these patients. And a proper
therapy is lacking.
The most commonly complained symptoms (autonomic activation, fatigue, somatoform
disorders, and decreased pain threshold), according to our observations, occurred more
frequently or appeared as more intense in association with increased solar activity, as
reported in websites.
As publications on the biological effects of solar activity have exponentially grown, an
increasing number of pathological effects in humans have been evidenced. Albeit
different theories have been posited, still there is no consensus on their mechanisms of
action (3).
Interestingly, bilirubin has a similar structure to porphyrins, capable of causing serious
pathologies (4) and to photosensitive pigments with important biological functions in living
organisms, such as phytochrome (5), which have activation peaks in the solar spectrum.
Furthermore, bile excretion is stimulated by cholecystokinin, which many studies have
linked to the stress response (6). Incidentally, physical and mental stressors are considered
risk conditions for patients with Guilbert’s Syndrome. On the other side, we observed that
the application of relaxation techniques, which reduces arousal, temporarily reduces the
sense of fatigue and malaise as well as psychosomatic symptoms.
Systematic studies are warranted to verify relationships between solar activity and
potentially sensitive organic compounds as possible physiological and pathological
mechanisms, but more generally there is the need of new models in research.
References:
1) Vítek L., Tiribelli C. Gilbert’s syndrome revisited. Journal of Hepatology, Volume 79, Issue
4, October 2023, Pages 1049-1055. https://doi.org/10.1016/j.jhep.2023.06.004
2) Hamilton F. W., Abeysekera K.W.M., Hamilton W., Timpson N.J. Effect of bilirubin and
Gilbert syndrome on health: cohort analysis of observational, genetic, and Mendelian
randomisation associations, BMJ Med. 2023 Jul 12; 2(1):e000467. https:// doi: 10.1136/bmjmed-
2022-000467
3) Sarimov, R.M., Serov, D.A., Gudkov, S.V. Biological Effects of Magnetic Storms and ELF
Magnetic Fields. Biology 2023, 12, 1506. https://doi.org/10.3390/biology12121506
4) Granata, F., Nicolli, A., Colaiocco, A., Di Pierro, E., Graziadei, G. Psychological Aspect and Quality of Life in
A Diagnostics Porphyrias: Review. 2022, 12, 1193. https://doi.org/10.3390/diagnostics12051193.
5) Yi C., Gerken U., Tang K., Philipp M., Zurbriggen M.D., Köhler J., Möglich A., Plant
phytochrome interactions decode light and temperature signals, The Plant Cell, 2024, 36, 4819–
4839 https://doi.org/10.1093/plcell/koae249
6) Asim M., Wang H., Waris A., Qianqian G., Chen X. Cholecystokinin neurotransmission in the
central nervous system: Insights into its role in health and disease, BioFactors. 2024; 50:1060–1075 https://DOI: 10.1002/biof.2081
Stefania Borgo, MD
Center for Research in Psychotherapy, Rome (Italy)
https://www.crpitalia.eu
Email: stefania.borgo@fondazione.uniroma1.it
Stefania Borgo
Neurologist and Psychiatrist and Psychotherapist is the Scientific Director of the Center for
Research in Psychotherapy, Director of the post-graduate School of Specialization in Cognitive-
Behavioral Psychotherapy and Psychosocial Intervention, Director of the online Journal
Psychomed.
Conflicts of interest: none
Lucio Sibilia, MD
Center for Research in Psychotherapy, Rome (Italy)
https://www.crpitalia.eu
Email: Lucio.Sibilia@fondazione.uniroma1.it
Lucio Sibilia
Neurologist, Psychiatrist and Psychotherapist, is a former Faculty in Psychiatry and Clinical
Psychology of Sapienza, University of Roma (Italy). He is currently president of the Center for Research in Psychotherapy (CRP), where he works and teaches Cognitive-Behavioral
Psychotherapy.
Conflicts of interest: none.
Lucio Sibilia
