Hi there. I have a simple, embarrassing question. When I get tired from lack of sleep, very often the next day I am extremely gassy. I emit these noxious farts that can clear a room and induce retching. When I’m not tired, I’m almost never gassy, and the occasional fart doesn’t have much odor to it. Even when I eat spicy food, I’m usually ok.
So why does being tired let loose the flatulent floodgates?
When you’re tired, you stop exercising and rest. (Not necessarily in the sense of “doing exercises” – any physical labor. And sitting or reclining is nearly equally ‘restful’ to the muscles as sleep.
When you’re exercising, your circulatory system’s primary function is to deliver nutrients to where they are being burned. When you’re resting, it can divert efforts to enabling digestion, assimilating digested nutrients, and rebuilding the reserve used during exercising.
You produce gas during digestion. You do most digesting while resting. Q.E.D.
Hmmmm, that explains the prevalence, but not the odor.
Do you tend to eat differently when you stay up late? If you eat foods that you don’t otherwise (say, lots of ice cream or other fatty foods), you’ll have different… digestive results than you would otherwise.
No, no changes in diet. I just fart like a motherfuck when I’m tired.
I don’t have an answer, except to say I have similar problems.
If I don’t get a good night sleep (less than 4 hours) then I’ll feel gassy the next day, though not sure on any change in odor. 
I wish I wasn’t sure…
I get that too when I’ve been up late and I believe the topic was broached on the boards before.
Albeit without an answer that time IIRC, thanks Polycarp.
Wouldn’t this also mean that the anal sphincter muscle would be relaxed, too? And that would seem likely to cause more passing of gas.
But I don’t see any explanation for the alleged change in odor. I really wonder if that is just confirmation bias. Note that it takes about 24 hours from the time food is eaten until the non-digested part exits the body. The part of digestion that produces the gas is mainly in the lower colon; it will was processing that food about 12-8 hours ago. So the gas is coming from the food you ate yesterday, and which your colon was digesting early this morning. I can’t see an explanation for how your colon would know at breakfast time that it should process the food in a more ‘gas-generating’ manner, because you are going to stay up late & be tired tonight.
I know from experience that certain foods that give me gas will give it to me well before 12-18 hours after eating, sometimes in as little as 1.5-2 hours later. (Certain foods -> certain distinctive odors, so I can track this with some precision.) Are you sure that the time lag is generally true?
The colon has pockets of gas separated by pockets of food. The whole train of “pockets” has to move along to get some of those gas pockets to the back door(so to speak). The more still you are, the slower the train moves. The longer the gassy foods linger in the colon the more gas is produced and the further along the decomposition process is the smellier that gas will be. Does that answer the question?
So, to counteract this problem, I should exercise the morning after a sleepless night?