Have you ever wondered why you seem to have digestive issues or bloating if you have dinner late nights or sleep late? If you travel across time zones quite frequently, you may feel gassy or bloated! Have you ever thought why? All this is linked to disturbances in your circadian rhythm or your body’s biological clock. Based on our time zone, weather conditions & pollution level, our body has a unique biological clock & any deviation from the same can increase our risk of metabolic & digestive disorders.
Let us discuss how disruption in circadian rhythm can impact our digestive system!
Our digestive system has its own biological clock & intrinsic rhythms that communicate directly with circadian rhythms of other organs. Sleep & other circadian factors influence our appetite, nutrient absorption & metabolism. Any disruption or deviation from our circadian rhythm can increase our susceptibility to digestive disorders including IBS, acid reflux, ulcer, inflammatory bowel issues & gastrointestinal cancer.
It is no brainer that our biological clock & sleep cycle impact the physiology of every organ of our body system. These drivers influence brains’ control over autonomic nervous system & endocrine system through this 24/7 cycle. The bi-directional communication between brain & gut includes feedback loop to sleep & circadian rhythm pathways. The circadian rhythm helps the body get prepared for anticipated events. As a master clock, Suprachiasmatic Nucleus(SCN) is responsible for coordinating the circadian rhythm throughout the body. The rhythm is not exactly 24 hours & hence must be adjusted for environmental time clues. The most relevant time clue is daylight. Besides, food & sleep also impact the phase of the biological clock. Sleep is normally aligned with decreased circadian rhythm for wakefulness. Some regulatory functions may be impacted by sleep patterns while others exhibit circadian patterns. As such the sleep dependent factors may be improved by making adjustments that influence sleep while circadian rhythm factors may be made more efficient by adjustment of factors related to other circadian parameters. The below comparison explains the impact on both sleep & other circadian related factors on various digestive & metabolic issues.
In this blog( part1), we will be discussing about acid reflux & Gastroesophageal reflux disease(GERD)
One of the other circadian rhythm(CR) indicators, food, tends to enter specific CR oscillators which is said to influence our food intake & eating behaviour. A number of hormones such as ghrelin, leptin, insulin & glucagon oscillate in a daily fashion to anticipate activities such as feeding. A major portion of these oscillators reside in the stomach( specifically Ghrelin). This rhythm is related to availability of food & tends to disappear in the darkness.
Digestion begins in the mouth as a process of chewing, salivation & swallowing. These processes are linked to waking state. Although chewing declines during sleep, saliva decreases to zero during sleep. Saliva pH also decreases during night as well as swallowing rate decreases by 80%( 25 times per hour to 5 times per hour) during sleep/night. Infact lower esophageal sphincter(LES) also decreases tone during sleep but stays above that of intragastric pressure. Therefore during sleep, esophagus becomes more vulnerable to gastric acid by low swallow rate, decreased saliva volume & low chewing rate.
Gastroesophageal reflux disease( caused by the condition of acid reflux) is generally impacted by both circadian & sleep factors. Both these states influence esophageal reflux by diminishing or eliminating the natural defenses against reflux events. Reflux events that occur during sleep are less frequent as compared to those that occur during wake but have longer contact time due to delay in esophageal clearance. This reduced clearance & increased mucosal damage is due to sleep induced factors such as reduced swallowing times, diminished saliva production( saliva aids in digestion process through release of enzymes), decreased swallowing rate & decreased LES pressure & circadian related factors such as increased gastric production & delayed emptying of gastric acid. he loss of esophageal protective mechanisms and greater acid exposure with reflux events is correlated with the occurrence of esophagitis and risk of mucosal damage
Essentially, during night, like our brain, our stomach & gut also shuts down. As such our intestines & guts do not move food to the digestive tract. Therefore when we eat late at night, our food sits there. As explained above, our stomach builds up & starts releasing gastric acid. As such food sitting near to the small intestine acts as a feast for bacteria living in the gut & some of them including archaea starts moving to the small intestine leading to SIBO.
During day time, circadian rhythm of our mouth produces saliva that neutralises stomach acid & aids in digestion process. During the evening, our mouth stops releasing saliva. This is the reason we do not salivate during our sleep. When you have a lot of acid & food is not going down, acid comes to our mouth leading to acid reflux. Having your last meal early can help you reset your circadian rhythm of the digestive system.
In our next series of blogs on circadian rhythm-digestive system connection, we shall discuss Irritable bowel Syndrome , irritable bowel disease & gastrointestinal cancer.
If you sleep late at night &/ or eat late & are suffering from symptoms such as bloating, gassy, constipation or even experiencing depression or anxiety, disturbance in your circadian rhythm may be a spoilsport in attracting acid reflux. Want to know more how to reset your circadian rhythm by decoding your gut microbiome composition? Sign up for our free discovery call here.
Source: https://www.researchgate.net/publication/11582874_Intragastric_acidity_and_circadian_rhythm
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