Dozing at your desk can be costly.

Power napping has many fans, but falling asleep at the desk could have cost one German bank millions and an employee her job.

A bank clerk nodded off for a second while processing a transfer request and held down the number 2 on his keyboard, changing the amount from 62.40 euros to 222 million euros ($293 million) or 222, 222, 222.22 euros exactly, according to testimony before a German court.

The mistake was spotted and corrected by a routine internal system check, but not before the pensioner's payment request had been approved by a colleague.

On April 2, 2012, she was found to have spent less than 1.4 seconds examining 603 payments, between 1.5 and 3 seconds examining 105 payments, and more than 3 seconds reviewing 104 payments, the court said. Little wonder the error slipped through.

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The employee, who had been with the bank for 26 years, was promptly fired for failing to check the payment slips. She took her case to the regional labor court in Frankfurt, Germany's financial capital, and won.

The court ruled that the 48-year-old be given her job back. The mistake was serious, it said, but the bank should have issued a warning rather than firing her.

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A year ago, German media reported that Commerzbank (CRZBF) mistakenly deposited 200 million euros in a customer's account after he sold shares worth 20,000 euros.

The customer moved 10 million euros into an account at another bank. Commerzbank successfully reclaimed the full 200 million euros but failed in its attempt to claw back 12,000 in interest.