He was in his second year with the Ravens after they had selected him in the sixth round of the 2013 NFL draft, and Jensen found himself exhausted during the day. He was losing weight and muscle mass without even trying.
The turning point occurred after a preseason game against the San Francisco 49ers on Aug. 7, 2014, that his parents had attended. After his parents, Dean and Jane, returned home, his father called.
"I remember my dad calling me and saying, 'Hey, you need to figure out what's going on. You were really rude to your mom, and she was really upset,' " recalled Jensen, who was released by the Ravens that same preseason and signed to the practice squad. He is now the projected starting center for 2017.
"I thought I was being normal. That was the waking moment for me, when my dad called me and said, 'You either need to quit football or figure out what's going on because you're not acting like my son.' "
A week-and-a-half later, Jensen took part in a sleep study and discovered he had sleep apnea, a disorder characterized by stoppages in breathing while sleeping that can result in a loss of oxygen to the brain. Sleep apnea has been cited as a contributing cause in the deaths of Hall of Fame defensive end Reggie White, Star Wars actress Carrie Fisher and comic actor John Candy.
He had passed a sleep apnea test when he was a junior at Colorado State University-Pueblo, but the more intensive sleep study in 2014 determined he was not breathing for up to 40 seconds at a time. He said doctors told him that in the nine hours he spent in bed, he was getting just 90 minutes of actual sleep.
Jensen has since been using a CPAP (continuous positive airway pressure) machine to help him control his sleep apnea, which caused him to drop from 315 pounds to 290 and increase his body fat percentage from 23 to 28.
"It really has saved my life and it really did save my career," he said of getting diagnosed. "If I hadn't figured that out, I probably would have been out of the league because I was sick and I was losing weight and I couldn't keep my strength up. So to me, it was very important to get tested and find out that I had that."
According to the National Institute of Health's National Heart, Lung, and Blood Institute, 12 to 18 million adults in America suffer from sleep apnea. A recent study by the New England Journal of Medicine found that 34 percent of NFL linebackers who participated in the study are affected by sleep apnea.
"The problem is the retired NFL players who don't lose the weight and those who were thin before and gain weight after they retire," said Dr. Casey Batten, director of primary care sports medicine at Kerlan-Jobe Institute in Los Angeles and lead primary care sports medicine physician for the Los Angeles Rams. "A lot of offensive linemen lose weight afterward because it's not their natural weight. It's the ones who are maybe not linemen that are becoming inactive and maybe have to more vigilant after they retire versus those who are larger during their careers."
Weight gain has played a significant role in former Ravens quarterback Scott Mitchell's battle with sleep apnea. Mitchell, who played for the team in 1999, said he woke up with pounding headaches and severe throat dryness and joked that his wife threatened to leave their home because of his snoring.
Diagnosed with sleep apnea in 2010, Mitchell has been using a CPAP machine as he works to keep his weight under 255 pounds, which he has identified as the threshold for his apnea.
"I forgot what it was like just to be able to sleep," said Mitchell, who appeared on the reality show "The Biggest Loser" in 2014. "It was like, where has this been? It was a life saver, no question about it."
Former NFL offensive lineman Damien Woody also was diagnosed with sleep apnea. After appearing on "The Biggest Loser" with Mitchell, Woody, who is now an NFL analyst for ESPN, said he has lost 110 pounds and no longer uses his CPAP machine.
"From a mental standpoint, my mind is so much clearer and so much sharper," he said. "I have a lot more energy. My wife and I have seven kids, and I have the energy to not only do the day-to-day tasks, but also all the things that are required with the kids. My joints feel better. My overall health is a lot better now than when I was carrying all of that weight around."
Batten, the Los Angeles Rams doctor, said many people are unaware of the dangers of sleep apnea, which can contribute to heart disease, strokes and other life-threatening conditions.
"If you look at the general symptoms in those people, it could be something as simple as a headache or they just feel not rested or tired during the day, and with their schedules and what they do, that can be perceived as normal," he said. "But it really could be coming from sleep apnea. So that is sort of a silent killer like hypertension. They feel OK, but they obviously have an underlying problem. We know that sleep apnea contributes to high blood pressure, diabetes, and other issues that can definitely shorten one's life span."
Mitchell, the former Ravens quarterback, said he can't remember a single teammate or player discussing complications related to sleeping.
"Even when Reggie White died, people were saying, 'Well, that was rare and unusual, and I don't have that problem. So it's not that big of a deal,' " he said. "I just don't think people think about it."
Woody, the ESPN analyst, did not disagree with the notion that the current generation of players is more concerned about torn ACLs and high ankle sprains than they are about sleep apnea.
"I think the one thing about a lot of young guys is they think they're invincible," he said. "They get into the league, and they're having the times of their lives. The biggest thing I would say to guys who are battling their weight is, you better get a hold of it now. You've got to have good habits now because it's only gets harder as you get older. Your metabolism slows down, and once you get out of the league, you're not as active as when you were playing and burning a lot of calories."
Former Ravens offensive lineman Wally Williams is working with a company called DreamSleep to connect people having trouble sleeping with medical professionals who can help. Williams, whose mother and other relatives battled sleep apnea, said better sleep is beneficial for everyone.
"We're talking about a proper night's rest," he said. "You're looking for every type of aid there is in the world to try get the edge – whether that's in the classroom or corporate America or athletics – and this is one thing that we feel strongly about in saying that when you're cutting off your breathing mechanism every night 10 to 15 times per night, how can you say you're getting a proper rest to go out every day and maintain your job? That's what sleep apnea is."
Jensen is open to talking about his battle, even suggesting to the father of tight end and teammate Maxx Williams to get tested for apnea. "It's good to spread the word and be able to help guys who need it," he said.
It's important for any person who even thinks he or she is suffering from apnea to see a doctor, Jensen said.
"Sleep is a huge deal," he said. "There are obviously studies done that say if you don't get enough sleep, it affects your performance for professional athletes and people out there working 9-to-5 jobs. If you don't get enough sleep, you're not going to perform at your best level."