Your new breakfast of champions likely comes in a fast-food wrapper.

Morning is the new hot time for the super-competitive, quick-service restaurants, who each want to entice hungry, possible groggy, customers. National chains, already duking it out for lunch and dinner, now want a chunk of those a.m. dollars.

McDonald’s unveiled its Triple Breakfast Stacks (two slices of American cheese, two sausage patties, bacon and egg and served on a a choice of McMuffin, biscuit or McGriddles cakes) Tuesday. During Burger King parent company Restaurant Brands International's earnings call on Wednesday, CEO Daniel Schwartz discussed the popularity of the breakfast menu at its Tim Hortons chain in Canada. And rumors that Chipotle Mexican Grill will get into the breakfast game weren't quashed during its earning call Thursday; CEO Brian Niccol – the man who helmed Taco Bell during its successful breakfast push – evaded an analyst's question on the topic.

More:Which new technologies make vehicles unreliable?

More:Google CEO says it has fired 48 employees for sexual misconduct

More:Stock market: Should investors fear a correction, or 10 percent drop?

"Breakfast is still the meal occasion most likely to be prepared and eaten at home," said David Portalatin, vice president and food industry adviser for the research firm NPD Group. "It’s sort of the final frontier for restaurants."

Breakfast is the only part of the day that has seen growth, according to NPD. U.S. fast-food restaurants had close to 41.2 billion visits in the 52 weeks ending in August, including 7.3 billion-plus for breakfast. Those numbers are from up from more than 38.9 billion– almost 6 billion of them breakfast – during the same period in 2009.

The battle for breakfast is in full force. Chains from Sonic to Starbucks have been growing their morning-inspired menus. Plus, those already deeply invested in the morning continue to push the breakfast angle, from the limited-time Dunkin’ All You Can Meat breakfast sandwich (egg and cheese croissant with two strips of bacon, two slices of ham and a sausage patty) to name-changing IHOP’s return to its pancake roots this summer.

"Companies have focused for so long on changes in lunch and dinner – your typical burger and chicken nugget options – that they haven't spent so much time innovating on breakfast," said Ernest Baskin, an assistant professor of food marketing at St. Joseph's University. "They are viewing it as white space, where they can introduce new things at relatively little additional costs."

Breakfast isn't always so bucolic, though. Wendy's attempt failed and even a morning move faces potential problems due to increased staffing and adding complexity – in the form of more ingredients and menu choices – to kitchens that are supposed to be fast.

When done right, though, breakfast provides room to grow sales and customer traffic, which pleases Wall Street.

"Lunch is historically the sweet spot for fast-food restaurants, and lunch is under attack," said Portalatin, pointing to the growing number of telecommuters and flex-time employees and the rise of the on-demand workforce. "The traditional notions of place and working patterns (have changed), so demand for fast-food lunch simply isn’t there."

Here are four reasons breakfast may become the most important meal of the day for many fast-food chains.

Easy menu modifications

Unlike your grandma's blueberry muffins, fast-food breakfast menus aren't made from scratch. In most cases, chains' morning food line-ups are simply riffs on their pre-existing lunch and dinner offerings. Companies reverse-engineer breakfast dishes, using ingredients and core menu items. Add an egg here; toss some fruit there.

"In most cases, they’re using products already have in their restaurants to create new sandwiches or tweak them here or there. They try not to bring in more products," said Peter Saleh, restaurant analyst at the financial-services firm BTIG. "In some cases, they try to scale thing backs (like) lower calorie counts and egg whites only."

Convenience is key

Most people have Garfield-esque feelings toward mornings: They hate them. The universal craziness of the a.m. rush to get to work can be alleviated slightly by sidling up to a restaurant and having your breakfast handed to you. Shaving a few minutes off that go-go-go period for a few bucks means the difference between a granola bar stuffed into a briefcase and a hot sandwich.

NPD's Portalatin called it a "genius invention."

"A breakfast sandwich provides the perfect, tidy little hand-held package of protein and carbs," he said. "I can have it and call it a snack or pair with fries and fruit and coffee and call it breakfast, or I can have two breakfast sandwiches and not spend that much more."

It's OK to toss the toaster

Going out for lunch and dinner has been the norm for so long, but turning to restaurants for breakfast is, for many, still a no-no, save for the occasional weekend brunch. Now, bought breakfasts are gaining acceptance, a trend with roots in a key part of the morning meal – a cup of caffeine.

"You can trace bit back to the coffee business," Baskin said. "A lot of people made coffee on their own. Now, people have transitioned, and coffee is easy to get to go."

Breakfast on the go is now a given for those coveted young customers ages 18 to 34. Thirty-three percent eat their weekday breakfast en route to another location, according to Technomic. Plus, this group eats a fast-food breakfast an average of 4.3 times a month, compared to 3.7 times for consumers ages 35 and up.

A built-in fan base

"If you like X, why not try Y?" is a textbook way to get customers to come back. For companies that serve traditional later-day foods, like burgers, a strong pitch to their p.m. regulars strikes a chord.

While the tabs might not be high as they are for lunch and dinner, breakfast screams out for complementary add-ons, like coffee.

That's someone like Jesse Wilson of Fulton, New York, who eats at Taco Bell three times a week, including once for breakfast.

"I discovered Taco Bell breakfast maybe a year ago, and I just love it. It tastes great," said the 28-year-old salesman, who spends about $8.50 for a sausage Breakfast Crunchwrap or a steak Breakfast Quesadilla, plus a drink. "It’s a deviation from a bowl of cereal or oatmeal in the morning" at home.

Follow USA TODAY reporter Zlati Meyer on Twitter: @ZlatiMeyer