- Updated on November 1, 2020
Feeling Sleepy After Eating: Breathing and Digestion
For most people, sleep produces the worst effect on personal breathing and body oxygenation. The next most damaging factor is eating, especially eating too much. You can easily confirm the strong negative effects of these factors on the body oxygen test. It is common that the body-oxygen test results are reduced by 20-40% or by 5-10 seconds due to hyperventilation.
Overeating produces a serious biochemical shock on the whole organism due to factors related to heavy breathing. Feeling sleepy after eating and even falling asleep after meals are typical signs of such biochemical shock. This effect of being sleepy after eating meals is much stronger when junk foods are consumed, and especially after overeating (see the second half of this page for more info about this effect). We start to generate free radicals (causing oxidative stress or damage to cells) when the body-oxygen levels drop below 20 s (see the body-oxygen test below).
Effects of overbreathing on digestion
Hyperventilation is an important part of our “fight-or-flight” response. In such conditions, large muscles require an increased blood supply to improve chances of survival. That means that more blood would be diverted to the large skeletal muscles, resulting in less blood for vital organs including the organs of digestion.
Indeed, British and Japanese scientists found decreased blood flow to the liver (Hughes et al, 1979 and Okazaki et al, 1980), while American medical doctors confirmed the same effect for the colon (Gilmour et al, 1980). Hence, the more heavily we breathe, the less blood and oxygen goes to our digestive organs (and the brain too) due to hypocapnic vasoconstriction.
Almost a century ago, Yale Professor Yandell Henderson from Yale’s School of Medicine found that low CO2 in the arterial blood (due to hyperventilation) resulted in the loss of tone of the intestines, producing extreme intestinal congestion. Saturation of the blood with CO2 rapidly eliminated the congestion (Henderson, 1907). The results were published in the American Journal of Physiology.
Warning: In some people, mild voluntary hyperventilation can almost halt their digestion so that it can take up to 5-7 hours or more to empty the stomach. Note that such “experimentation” can be dangerous leading to the aggravation of existing gastrointestinal problems. Breathing less (or hypoventilation) can also make some digestive problems worse.
Hence, chronic hyperventilation can interfere with normal digestion. Poor blood and oxygen supply can lead to a lack of digestive enzymes, accumulation of metabolic waste products, slower digestion, putrefaction of some foods and nutrients and mal-absorption. Systematic research in this area is absent and there are more questions than answers.
From a practical viewpoint, the above suggests that lower CPs (with less body-oxygen content) correspond with slower digestion. For example, a person with the normal breathing pattern, it takes about 2 hours to digest a regular meal (when almost no food is left in the stomach).
The same meal for a sick individual (e.g., 15 s CP) with an ineffective breathing pattern would need 1-2 hours more of digestion. The person with normal breathing after this meal would still be reasonably fit and able to exercise (not very rigorously, of course) after eating the same meal. The sick person would definitely need a rest.
Feeling sleepy after eating (for overweight people)
Many modern people, especially obese ones, feel sleepy after eating. This indicates overeating and ineffective breathing at the same time. The solution to this common problem for obese people is to practice reduced breathing so as to prevent hunger and eating fats and complex carbohydrates.
Any time an overweight person eats complex carbohydrates or fats, his body-oxygen levels and breathing immediately become much worse. Furthermore, hunger for starches and fats indicate a state of stress and lower CP with a higher heart rate.
What is the mechanism? Why can hyperventilation cause obesity?
According to Russian Buteyko research conducted by Russian medical doctors, CO2 is also responsible for the control of permeability membranes of fat cells. When we hyperventilate, due to low CO2, glucose is driven from the blood into fat cells and the blood glucose level naturally becomes low just due to hyperventilation alone.
Since glucose is crucial for the brain and well-being, it is sensible to eat in a manner that increases blood sugar levels up to the norm. Eating more intensifies respiration and this leads to the formation of a vicious circle: hyperventilation drives glucose into fat cells; the person gets hungry; he eats more and … hyperventilates more. Hence, over 70% people “naturally” gain weight when they hyperventilate.
Conversely, when people start to slow down their breath while practicing reduced breathing (especially with the DIY breathing device or the Frolov device), they naturally have less hunger and, if they start eating only when really hungry, they can easily lose weight. Physical exercise with only nasal breathing is another great way to fight obesity.
These are the most natural methods or techniques to lose weight and increase body-oxygen levels. Moreover, breathing less makes obese people more alert and more energetic. All these factors make breathing retraining more advanced than other weight loss techniques.
Be observant. When we are acutely sick with flu, cold or another infection or disease, our CP probably decreases about 2 or more times from its usual level. What happens with your digestion? How would you feel if you were to eat your regular meal while sick? What would happen with your CP? Which meals and foods do you prefer when you are sick?
Questions. For primitive people, it was vital to defend themselves any time, day and night, including after meals. Could they be physically strong and mentally fit after meals if their usual CPs were about 20-25 s (as in a modern population)? What would you expect their usual CPs to be?
Breathing exercises. Constipation Pain Relief: How to relieve constipation pain using 1-2 minutes simple breath work.
Gilmour DG, Douglas IH, Aitkenhead AR, Hothersall AP, Horton PW, Ledingham IM, Colon blood flow in the dog: effects of changes in arterial carbon dioxide tension, Cardiovasc Res. 1980 Jan;14(1):11-20.
Hughes RL, Mathie RT, Fitch W, Campbell D, Liver blood flow and oxygen consumption during hypocapnia and IPPV in the greyhound, Journal of Applied Physiology, 1979 Aug; 47(2): p. 290-295.
Okazaki K, Okutsu Y, Fukunaga A, Effect of carbon dioxide (hypocapnia and hypercapnia) on tissue blood flow and oxygenation of liver, kidneys and skeletal muscle in the dog, Masui, 1989 Apr, 38 (4): p. 457-464.