Former Olympian Victoria Pendleton has said she feels "psychologically and physiologically damaged" since having to pull out of a Mount Everest climb attempt earlier this year.
In May, the gold medal-winning cyclist was on course to reach the summit of the world's highest mountain with TV presenter and adventurer Ben Fogle, but was advised by doctors to cut the trip short due to health issues.
She has now said she has been coping with depression since then, and that she is still very unwell.
Pendleton, 37, told Radio Times magazine: "I've been suffering with depression since I got back from Everest.
"I feel psychologically and physiologically damaged.
"It's really put me through the wringer, and that has been harder than any disappointment about not making it up to the summit.
"It's like I've taken a real battering. I've never felt so overwhelmed with illness."
Pendleton was forced to pull out of the trip due to struggling with oxygen deficiency at 21,000ft, which she said gave her symptoms of "a horrific headache, like knitting needles sticking in the back of my skull".
"You act like you're very marginally drunk, it's not unpleasant, you're not totally suffering, but signs of the onset of a cerebral edema are very subtle," she said.
"You have to rely on others recognising it."
She said that, upon returning home to the UK, doctors told her that oxygen depravation can trigger depression.
"But I felt even further away from myself then," Pendleton added.
"They've assured me that it's quite a normal thing and in time it will pass. I've been having good days and bad days. You just have to grin and bear it."
She also said that she was blighted with chest and ear infections that took "three weeks of antibiotics to get over", and that it sent her into "despair".
Pendleton trained for 18 months for the Everest expedition, which she undertook with Fogle and mountaineer Kenton Cool, for the British Red Cross in a bid to highlight the environmental challenges mountains face.
Their efforts will be shown in a three-part series called The Challenge: Everest, which starts on CNN later this month.
Since retiring from cycling, Pendleton has become a professional jockey, and finished fifth in the 2016 Foxhunter Chase at the Cheltenham Festival.
She was also a contestant in the 10th series of Strictly Come Dancing, where she was partnered with professional dancer Brendan Cole.
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