The 73-year-old presenter, who has starred in the Channel 4 show since 2011, said he struggles to sleep as the overload of numbers and words from the blue cards in the game play on his mind at night.
He spilled: “I can’t b****y sleep after a day at Countdown.
“The only thing about Countdown that I don’t like is that my mind is spinning at the end of a day,” he added: “We do five a day and you see all these numbers and words spinning around.”
Nick, who also starred in The Apprentice as Lord Sugar’s adviser for nine years, said the team are forced to keep up their “energy levels” as the amount of episodes have increased.
He told The Mirror: “We are doing 260 episodes a year. They have upped it.
“We have got to keep up the energy level.”
Despite his struggle to get a good night’s sleep, the TV veteran insisted he wasn’t planning on leaving the daytime show anytime soon.
He added: “We are very proud of the show. I will keep doing it as long as I can. I am honoured.”
Nick also said he would like to see the long-running format moved to a later time in a bid to give the show a more prominent position on prime time TV.
“I say 5pm is nice, but I am not complaining,” he quipped.
Meanwhile, his co-host Rachel Riley, 32, recently spilled that if viewers got to see what happens behind-the-scenes on Countdown and the comedy spin-off show 8 Out Of 10 with Jimmy Carr, 45, their careers would “end.”
She said: “Each show takes three hours to record and is cut down to 45 minutes. So the stuff on the edit floor can be even funnier.”
The TV star continued: “The lawyers have to be involved to make sure some of it doesn’t go out because it would end all of our careers.”
The former Strictly Come Dancing star replaced Carol Vorderman, 57, on the daytime show in 2009 and spilled that the team often have late night parties.
She told the publication: “Jimmy throws a good party regularly. He’s a really good host. I wouldn’t name names but there are certainly people who’ve done all-nighters there and then gone to work the next day.
“I’m lucky that I haven’t often been working the next day, because you can end up at 4am in the hot tub, it has been known. A few hangover cures are definitely needed after that.”