It’s the most wonderful time of the year, so why do so many of us feel so crummy? Bloated stomachs, heartburn, constipation and diarrhea don’t appear in Hallmark movies and holiday songs.

Sure, we eat and drink more, but there’s more to it. The anxiety, fear and stress of gift buying, entertaining, dealing with troublesome relatives, choosing the right outfit, and simply getting through the season can literally make us sick.

“Many people call the gut our second brain,” said Rashna Staid, an internal-medicine specialist with the Marcus Institute of Integrative Health in Villanova. “It doesn’t think or reason for us like our regular brain does, but it does transmit all the emotions and feelings that we have.”

We all feel that connection at some point — maybe the flip-flopping you feel in your stomach before a public-speaking engagement or taking a test. “When you say, ‘I have a gut feeling,’ that’s real,” Staid said.

There are more neurotransmitters in our guts than in our brains, including serotonin, a chemical that helps with sleeping, eating, and digesting; dopamine, a feel-good hormone; and norepinephrine, which mobilizes the body for action. Outside influences — including what we eat, drink, and smoke — bombard our microbiome, the bacteria that live in our gut, and work with our immune system to protect us. Eighty percent of our immune system is actually in our gut, Staid said.

Regan Tilton, 37, went to an urgent-care clinic near her Society Hill home recently because she was feeling lethargic and anxious. This is the busy season for both her jobs, at Chilly Dog Sweaters and as a reiki practitioner, leading her to skimp on healthy eating and exercise.

“I was malnourished, and it was affecting everything in my body,” Tilton said. “You go from Halloween candy to Thanksgiving leftovers, right into Christmas. Around the holiday season, there are so many parties and things to do, and my regular schedule is off.”

She also laments going to work in the dark and coming home in the dark. “It doesn’t feel right to your system,” she said.

Now, Tilton is making sure she schedules time for herself, even if it means missing out on a party. She is mostly sticking to a plant-based diet, no meat or dairy and limited gluten and sugar. She has cut out coffee and is taking more yoga and reiki.

“There are more things that you’re obligated to this time of year, and you have to choose yourself,” she said.

A vicious cycle

That’s good advice, Staid said. “For some people who are under a lot of stress and are worried about things but don’t know how to deal with their anxiety, it causes them to have a burning pain or bloating in their abdomen. When you help them work through their stress issue, you make their gut issue significantly better.”

The head-and-gut relationship can become a vicious cycle, said Nitin Ahuja, assistant professor of clinical medicine in the division of gastroenterology at the University of Pennsylvania.

“More stress causes more pain, which causes more stress,” he said.

That’s especially true during the holidays, when we are coping with longer to-do lists, richer foods, more junk food and alcoholic beverages. When we aren’t getting needed nutrients and drinking enough water, constipation and bloating can occur, contributing to feelings of fatigue, depression and anxiety.

Bowel health can be affected by your state of mind, said Premysl Bercik, a gastroenterologist in Hamilton, Ontario and member of the AGA Center for Gut Microbiome Research and Education Scientific Advisory Board. “Acute stress can make your gut a bit leaky, so more bacterial antigen can pass the lining of the intestine and produce a low-grade inflammation in the gut,” he said.

“This can negatively impact your brain because inflammation anywhere in the body, through the release of pro-inflammatory mediators, can trigger anxiety.”

Plan to be well

Like so many things in life, gut health often is all about moderation.

“There’s a lot to celebrate around the holidays, so it’s OK to enjoy rich foods in moderation and even alcohol in a communal setting,” said Ahuja. Certainly, be cautious around foods that you know cause stomach distress. But don’t deny yourself completely.

And don’t go to the other extreme and make the excuse that you blew it, so you may as well continue to indulge, said Staid.

Try planning for intentional indulgences, followed by focusing on healthy whole foods that, thanks to your advance planning, you already have ready in your kitchen.

Reducing holiday anxiety goes beyond what you eat and drink. Plan to take time for yourself — even if it’s just a few moments of deep breathing.

Mindfulness-based techniques such as meditation, yoga, and other mind-body exercise are especially helpful in handling stress. If therapy helps you, don’t put it off until after the holidays, said Ahuja.

Making sure you get enough sleep is a key stress-reducer, and eating well and exercising are important for general wellness.

Staid advises staying close to people who make you feel good.

Among this doctor’s holiday prescriptions: “Avoid people who bring you down.”