A soothing pillow and warm duvet might not always lead to better rest. A 43-year-old-man, after having switched to feather bedding, began feeling extreme fatigue and breathlessness, and was diagnosed with "feather-duvet lung," according to a new case report.

The patient went to his doctor after experiencing three months of unexplained malaise, fatigue and breathlessness. The doctor first diagnosed the man with a lower respiratory tract infection. While the man's symptoms improved a bit after that visit, they worsened later that month, forcing him to take 14 days off work.

The man went back to the doctor with symptoms of increased breathlessness, such as when walking from one room of his house to another. "Going upstairs to bed was a 30 min[ute] activity as I could only manage two stairs at a time and then needed to sit and rest," the patient described in the case report. "I was signed off work and spent most of the time asleep."

Related: 7 Strange Signs You're Having an Allergic Reaction

His general practitioner ordered a chest X-ray, which was considered to be normal. But when Dr. Owen Dempsey, a pulmonologist at the Aberdeen Royal Infirmary in the UK, took a look, he disagreed and performed a more detailed CT scan. The scan revealed severe inflammation in the man's lungs.

After questioning the patient on what could be triggering this allergic reaction, Dempsey and his team found a potential source: the man's feather bedding. Blood tests revealed that the man's body had created antibodies to a compound that he inhaled from duck or goose feathers. The patient was diagnosed with what's called "feather duvet lung," a type of severe lung inflammation caused by an immune response to feathers.

Feather duvet lung is a type of "hypersensitive pneumonitis" in which the body's immune response to a particular outside trigger causes the lung's air sacs and airways to become inflamed. "I'm sure it happens much more than we realize," Dempsey said. What's more, there are many variations of hypersensitive pneumonitis, such as farmer's lung (where the allergen is dust from hay, corn or other crops) and wood-worker's lung (where the allergen is sawdust), he added. "You name it, it probably has been described."

The patient was given steroids, and switched his bedding to hypoallergenic synthetic materials. His symptoms improved rapidly within a month, and by six months he felt well again. After a year, his symptoms completely cleared and he is now fully recovered, Dempsey said.

"It doesn't affect me at all now and my life is pretty much as it was before," the patient wrote in the case study.

It's important for health care providers to "take really detailed histories" of the patients, Dempsey said. "That way they may uncover things in the environment that trigger lung disease."

When doctors don't consider these triggers, they may assume the disease is "unexplained," and diagnoses are delayed, or patients are treated unnecessarily or incorrectly, he added.

That being said, "people with pillows and duvets containing feathers shouldn't panic or throw them out," he said. But if they have chest symptoms such as cough or breathlessness, they should let their health care professional know, he added.

The findings were published today (Nov. 18) in the journal BMJ Case Reports .

Originally published on Live Science .