Police in Metro Vancouver are making roadside checks at 5 a.m., catching people who don't realize they're still drunk the morning after the night before, the CBC has learned.

A CBC Investigates crew recently spent a morning with local RCMP at a CounterAttack Roadblock at an entrance to Highway 1 heading east and watched them reel-in drunk drivers who thought they were safe.

It was during this filming that the driver of a minivan suddenly sped through road check, his actions caught on camera. The incident led to three arrests.

In addition, over the course of two hours that morning the roadblock caught three drivers, including one man in a pickup truck within the first 15 minutes.

He blew over .05, but less than the limit of .08. He got an immediate roadside prohibition and since it was his second warning, his license was suspended for 7 days and fined $300.

Two others blew way over the limit, over .08, and got an immediate fail. Their licenses suspended for 90 days and they were fined $500.

Car towed at drunk driving roadblock

One driver received his second warning, his license was suspended for 7 days and his car was towed. (CBC)

Cpl.  Robert McDonald with RCMP Traffic Services said the figures were pretty standard.

"We're happy we only got two full fails. [It's an] indication the system is working. People are not totally getting the word, but it's improving," said McDonald.

Among the few drivers who agreed to face a camera crew that early in the morning, there was surprise and confusion over the roadblocks.

Nijar Shajani, a forensic consultant and blood alcohol expert, says a 68 kg man needs two hours to eliminate the alcohol in just one beer.

"Sleeping does not reduce your blood alcohol level. It is the time factor that is important," said Shajani.

ICBC figures for 2012 show impaired driving caused by alcohol, drugs or medication is a contributing factor in 22 per cent of fatal crashes.

McDonald advises hungover drinkers to think twice before driving, even after "sleeping it off".

"If you're gonna drink, give it time before you get behind the wheel. Just an hour or two is not enough to dissipate all the alcohol from your body."