I have known many people, including my own mother, who suffered from heartburn or gastro-esophageal reflux disease (GERD). Frequently, they complain of pain at night and have wondered why they would have pain at night when they are not eating. The simple answer is that there is a surge of acid production by the stomach that occurs every night. This seems counterintuitive, but makes sense if you consider that nearly all aspects of physiology exhibit daily rhythms (referred to as circadian rhythms, Figure 1). These circadian rhythms are controlled by a “master clock” or set of neurons in the brain that is controlled by light signals, as well as “clocks” in the periphery. These clocks are controlled by gene expression cycles that regulate protein production.
The parasympathetic nervous system is the part of the nervous system that promotes energy conservation, food and nutrient absorption, and other “rest and digest” functions. This part of the nervous system is controlled by the circadian clock in the brain and is active during the night. Thus, in addition to the signals generated by eating, this nightly activity of the parasympathetic nervous system can trigger episodes of heartburn or acid reflux. Indeed, for those suffering from frequent nightly heartburn or GERD may find that taking the acid-blocking medication in the evening with dinner rather than in the morning is often most effective.
Further Reading
B. V. Vaugh, S. Rotolo, H. L. Roth, Circadian rhythm and sleep influences on digestive physiology and disorders. ChronoPhysiology and Therapy 4 (September 2014) DOI: 10.2147/ctps448061. Full Text
K. Eckel-Mahan, P. Sassone-Corsi, Metabolism and the circadian clock converge. Phys. Rev. 93, 107-135 (2013). PubMed
Other Articles about Circadian Biology in BioSerendipity
N. R. Gough, The Benefits of the Early Bird Special: Insight into Fasting and Longevity. BioSerendipity (12 September 2018) https://www.bioserendipity.com/the-early-bird-special/
N. R. Gough, Signals in Night Time Breast Milk Help Babies Sleep. BioSerendipity (23 August 2019) https://www.bioserendipity.com/night-time-breast-milk-helps-babies-sleep/
Cite as: N. R. Gough, Why is heartburn common at night? BioSerendipity (25 July 2017) https://www.bioserendipity.com/why-is-heartburn-common-at-night/.