But struggling Orient, who had taken a ninth minute lead through defender Matt Lockwood, saw their relegation fears disappear following Bradford City's defeat at Chesterfield.
In a dramatic opening O's made the early breakthrough when Lockwood popped up in the box and fired home his 11th goal of the season.
But Orient's joy was short-lived and after Adam Chambers headed narrowly wide and missed the opportunity to add a second, it was Forest who took control.
The visitors were level on18 minutes when the hugely-impressive Lester raced through from midfield and shrugged off challenges from Luke Guttridge, John Mackie and Lockwood before firing home across keeper Glyn Garner from 18 yards.
Suddenly, Forest were on fire and Garner saved well from Lester before the visitors struck again on 29 minutes.
Commons played a quick free-kick to Lester, who cut the ball back from the left to Commons and he crashed it home from 18 yards.
Little was seen of Orient as an attacking force and all they could muster before the break was a couple of efforts from top scorer Gary Alexander.
One of which was well saved by Forest keeper Paul Smith and the other flew over the top of the new stand.
After the break Forest were quick out of the traps and Garner had to be alert to save well from Grant Holt's close-range header.
But the visitors wrapped things up with a clever free-kick just before the hour.
Commons played in a neat lob and Lester raced on to the ball and beat the offside trap before firing home from 12 yards.
After that, the result was never in doubt, despite a couple of late efforts from Orient substitute Efe Echanomi.