Justin Bieber opened up about his substance abuse, mental health, and recovery process on his new YouTube documentary series "Seasons."

During the most recent episode of the series, the singer opened up about how he manages his anxiety and substance abuse recovery through unconventional methods.

Bieber said sleeping in a hyperbaric chamber and getting weekly IV infusions of NAD+ helps manage his symptoms, but the treatments don't come cheap.

According to Dr. Mark Calarco, while some patients have reported feeling better after both treatments, there are no clinical studies that prove either are effective in treating Bieber's set of conditions.

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In his new YouTube documentary series "Seasons," Justin Bieber opened up about how his childhood anxiety spurred his "dark period" in his late teens and early 20s when he was addicted to weed, lean (a liquid opioid), and pills.

Since getting sober, he has been diagnosed with anxiety, chronic mono, and Lyme disease, all of which can cause lethargy, anxiety, and heart palpitations.

"I think when you take somebody very young and they start to get horrible, crazy, crippling anxiety and it goes undiagnosed and you don't know what it is that you're feeling, you start to self-medicate because it makes you feel better," Hailey Bieber (née Baldwin), Bieber's wife, said.

His solution, Bieber explains in the 15-minute episode, is a mix of accepted and alternative treatments.

Though he said he relies on anti-depressants to "help me get outta bed in the morning," he also swears by sleeping in a hyperbaric chamber and getting NAD+ infusions administered through an IV — a common, though unproven, treatment for people battling substance abuse.

There's little evidence that hyperbaric chambers, worth thousands of dollars, are effective for anxiety

Bieber, pictured climbing out of the hyperbaric chamber in his studio. He also has one at home. YouTube Originals Bieber said that a large part of his anxiety management process has been the use of hyperbaric chambers, which he places strategically around his house and in his studio.

Hyperbaric chambers are enclosed rooms or pods in which patients sit while the air pressure is increased to three times more than normal ground-level air pressure. To do it in a clinic, individual sessions can range from $75 to $100.

Purchasing an individual chamber can set someone back thousands of dollars. Bieber has one at home and one in his studio.

"People are going to think this is some rich people s---," Hailey Bieber said, but she insists it's done wonders for her husband's mental wellbeing.

Demonstrating how it works, Bieber climbs into what appears to be large, blue bag. He described how the machine pumps oxygen into the zipped chamber, helping with his breathing and to decrease his stress levels.

"Mental health is so important to get on top of," Bieber said, sat half-in, half-out a hyperbaric chamber. "If you have ADHD if you have… something and you don't want to take medicine, I strongly believe in it."

Some doctors aren't so sure, though.

These kinds of chambers are typically associated with treating deep-sea scuba divers who experience huge changes in air pressure. According to the Mayo Clinic, hyperbaric oxygen therapy is typically a procedure used to treat burns, brain abscesses, gangrene, and other forms of infections in the body.

Recent research suggests the therapy could possibly be effective in treating certain mental health conditions like depression, anxiety, and PTSD.

But according to Dr. Mark Calarco, National Medical Director for Clinical Diagnostics for the American Addiction Centers, there are no clinical studies that prove hyperbaric oxygen therapy can help with anxiety.

"If it's done properly and in a safe environment, the risks are low, so maybe there's some benefit there on an individual level," Calarco told Insider. "But we don't know."

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The singer also gets NAD+ infusions through an IV to help with the effects of his years of substance use

The documentary also follows Bieber into the doctor's clinic, where he gets his weekly NAD+ infusions via an IV drip.

NAD+, or nicotinamide adenine dinucleotide, is a molecule that helps enzymes in the body function properly to give people energy. As people age, NAD levels typically decrease, causing fatigue and other symptoms like depression.

While NAD+ treatments have been used to treat conditions like Alzheimer's and Parkinson's disease, it isn't conventionally used to treat the effects of addiction like in Bieber's case. And like hyperbaric chambers, NAD+ infusions can be an expensive treatment options, costing $9,000 or more for a 12 day program in some cases.

Hailey Bieber explained to the camera that the infusions help to rejuvenate and rebalance the pleasure center in the brains of former addicts.

However, according to Calarco, who has been administering NAD+ infusions to patients for years, there are no clinical studies that prove NAD+ helps with Lyme disease or the impacts of addiction on pleasure centers of the brain.

"If people feel better after they have an infusion, whether they're in recovery or not, and their behavior is more aligned with recovery and they feel healthy and they're able to perform at a higher level, I think that's a good thing," Calarco said. "But I don't think we can go so far as to say it's a direct treatment for recovery."

That being said, Calarco said that if people have the time and money and are looking for answers beyond conventional treatments, infusions can be a good avenue to explore.

"[It can be a good avenue] for people who are looking for answers and who haven't gotten improvement through conventional methods," Calarco said. "I'm not saying they'll do it, we shouldn't be making these statements until it's been scientifically proven, but it's anecdotal."