Many of us feel sleepy after eating turkey and all the fixings on our Thanksgiving dinner table, but why?  

While we often blame our post-dinner drowsiness on the tryptophan in turkey, experts say that isn’t the full picture.

What is tryptophan?

Tryptophan is one of 20 essential, naturally-occurring amino acids, which are the building blocks of proteins, according to the nonprofit Center For Food As Medicine. 

When tryptophan reaches the brain, it is converted into the neurotransmitter serotonin and hormone melatonin, both of which are sleep-inducing, according to the organization. 

Does turkey really make you sleepy?

Research suggests that consuming tryptophan can help people fall asleep faster and improve sleep quality, according to the Sleep Foundation — but it’s not likely to cause someone to need an immediate snooze. 

“Turkey is reported to make us sleepy because it has a higher concentration of the amino acid tryptophan compared to some other types of meat,” registered dietitian Melanie Betz, founder and CEO of The Kidney Dietitian in Chicago, told CBS News. “In reality, brain chemistry is much more complicated than that. Turkey has many different amino acids, all of which get converted to different hormones and complete with each other in all of those pathways.”

Turkey isn’t the only food with tryptophan, either. It is found in poultry, meat, cheese, fish, eggs and seeds — some of which have even more of the amino acid than the Thanksgiving staple it’s so often associated with. 

“There are many foods, such as pumpkin seeds, ground pork, cheddar, swiss, provolone and mozzarella cheese, and yellowfin tuna that have more tryptophan per 100 grams than turkey,” according to the Center For Food As Medicine. 

What else could contribute to Thanksgiving fatigue?

Betz says multiple aspects of a Thanksgiving feast could add to the “food coma”-type tiredness many experience. 

“The sleepy feeling you feel after a turkey dinner is much more likely related to eating a large, delicious meal — and perhaps an extra glass of wine — than a surge of melatonin related to turkey,” she said, explaining that when you eat, “blood rushes to your intestines to pick up all of those wonderful nutrients from food, moving away from your brain, which can make you feel tired.”

And alcohol has a sedative or “downer” effect, she added, which can contribute to sleepiness on the holidays.

A self-described white supremacist charged with killing a man in a tent in southwestern Montana has pleaded not guilty to deliberate homicide and claims self-defense, while investigators say there are inconsistencies in the defendant’s story.

Daren Christopher Abbey, 41, told District Court Judge Peter Ohman on Tuesday: “I definitely plead not guilty. Dustin Kjersem tried to kill me,” the Bozeman Daily Chronicle reported. He also pleaded not guilty to tampering with evidence.

Kjersem’s death in October was initially reported as a bear attack after his girlfriend found his body in a tent south of Bozeman near Big Sky on Oct. 12.

Investigators found shot glasses and beer cans in the tent that suggested someone else had been with Kjersem on Oct. 10. DNA tests on a beer can matched two people in the state’s criminal database, Daren Abbey and someone believed to be Abbey’s twin brother, court records say. The brother was ruled out because he was serving a prison sentence.

Abbey told investigators that Kjersem, 35, threatened him and his dog with a gun and he attacked Kjersem, first with a block of wood and then by stabbing him in the neck with a screwdriver. Abbey initially failed to tell investigators he used an axe in the attack as well, court records say. He also told officers he found the axe both inside and outside the tent. He told officers he rinsed the axe and screwdriver off in the creek, court records say.

Abbey said he did not report the fight because he had a felony record. He acknowledged taking a cooler of beer and guns from the crime scene and then returning the next day to look for a beanie he believed he might have left there. He told investigators he also took two cellphones and items out of Kjersem’s truck, charging documents say.

Investigators previously said an axe, shotgun, revolver and cooler were “believed to have been removed from the scene of the crime.”

An inmate information document released by Gallatin County says Abbey listed an organizational affiliation with white supremacists, while state Department of Corrections records say his tattoos include an iron cross with a swastika.

Abbey is jailed with his bail set at $1.5 million.

Kjersem’s sister Jillian Price said her brother was a skilled tradesman and a doting father.

A GoFundMe set up for Kjersem’s children has raised more than $37,000.

Authorities from dozens of countries seized 225 metric tons of cocaine in a six-week mega-operation where they unearthed a new Pacific trafficking route from South America to Australia, the Colombian Navy said Wednesday. Officials said they had also seized “increasingly sophisticated” drug-laden semisubmersibles — better known as “narco subs” — that can travel 10,000 miles without refueling.

The latest phase of global naval operation “Orion” resulted in the seizure of more than 1,400 tons of drugs, including 225 tons of cocaine and 128 tons of marijuana, Navy official Orlando Enrique Grisales told reporters.

More than 400 people were arrested in the operation targeting oceans, coasts, rivers and ports around the globe in October and November.

The massive bust involved the security agencies of the United States, Brazil, Spain, the Netherlands and several other nations, as well as multiple international organizations.

The seizure deprived drug cartels of more than $8.4 billion dollars, according to a Navy statement.

Grisales said officials also seized a semisubmersible wood-and-fiber glass vessel on its way to Australia with five tons of Colombian cocaine.

This was the third such vessel discovered in this area, revealing a “new route” of trafficking with sophisticated boats that can cover the distance of some 10,000 miles without needing to refuel.

A kilogram of cocaine is sold for up to $240,000 in Australia, said Grisales — about six times more than the price in the United States.

“It is a route that is becoming increasingly profitable because prices are much higher in Australia,” a security source told AFP.

“Initially, these boats were used mainly to take the drugs out of the country and move them off the coast of Colombia and then transfer them to ships,” added the source.

“It has been found that these semisubmersibles, sometimes even submersibles, are now increasingly sophisticated, with very fine engineering.”

Semisubmersibles, which cannot go fully underwater, are popular among international drug traffickers as they can sometimes elude detection by law enforcement. The vessels are sometimes seized in Colombian waters while heading to the United States, Central America and Europe. In June, the Colombian Navy said it seized two “narco subs” off the country’s Pacific coast that together contained almost 5 tons of cocaine.

In February, Colombian authorities on a search-and-rescue mission for two missing fishermen found a “narco sub” loaded with more than 4 tons of cocaine. A few weeks before that, the Colombian navy intercepted a semisubmersible loaded with more than 1,000 pounds of cocaine in the Pacific Ocean.

The latest “Orion” operation also uncovered previously-unknown alliances between cartels from Mexico, Brazil, Colombia, Ecuador and Peru with groups from Europe and Oceania.

“It is not just a pyramid structure as the cartels once were. Today they are organized crime networks joined together,” said Grisales.

Colombia is the world’s biggest cocaine producer and exporter, mainly to the United States and Europe.

Last year, the South American country set a new record for cocaine production and cultivation of the coca leaf it is made from.