ear Grylls is kept awake at night by crippling anxiety.
The 44-year-old adventurer, who hosts Channel 4 survival show "The Island" - which sees participants placed alone on remote Pacific islands as a test of their survival skills - has admitted that some of the deadly challenges he's faced over the years, which left him close to death "over 100 times", have had a long-lasting impact on his mental health.
Admitting he's "lucky to be alive", he said: "I do suffer anxiety a lot and lie awake at night if I am nervous.
"I could have died over 100 times already. I should be dead.
"Nowadays my overriding thoughts are gratitude to be alive. I feel so lucky. There's been incidents over the years in the wilds which could and should have finished me off."
Bear - who has sons Marmaduke, 12, Jesse, 15, and Huckleberry, nine, with wife Shara - believes his anxiety is worse now as he has a family to think about.
He added to the Daily Star newspaper: "I probably get more nervous nowadays than I ever used to when I was younger. Life has made me more fragile. Maybe I have more to lose now."
The former SAS servicemen previously revealed some of the scariest moments of his career, including breaking his back in a parachuting accident in 1996, and a near-death experience climbing Mount Everest, two years later.
He said previously: "One of the darkest times for me was when I broke my back in a freefall parachuting accident in southern Africa."
And on surviving his climb to Everest's "Death Zone", he recalled: "It was -38 degrees and I felt like death. Blinding migraine, dehydrated, hungry, frozen and above all scared deep in the pit of my stomach. It was the waiting.
"The tension of knowing that ahead is the final 24-hour climb into the Death Zone where the level of fatigue, pain and risk becomes frighteningly high. "One in six climbers at that stage were losing their lives, and that plays on your mind as you wait."
When Bear is "in-the-moment", all of his anxiety and nerves are disguised by adrenaline.
He added: "I have always hated that feeling of nerves. I just want to begin - then I know it all becomes a process as you lose yourself (and your fear) in the adrenalin of the moment."