The article is poorly phrased -- I believe the "in a row" applies to (7+ hours of sleep) instead of (20 days of 7+ hours of sleep).
In other words, just the seven hours of sleep has to be contiguous?
"In a row" wouldn't normally be used with units of time like that, it implies something happening each time (in this case the 7+ hours of sleep, happening each night)
Well, you have a whole year to get a consecutive 20 days. I think the goal is to build a habit.
Bertolini is quoted as saying "up $500 a year". Assuming he meant "up to $500 a year", a run of fewer than twenty days would lead to a reward. Presumably only the longest run of the year counts.
... especially if you have family members (like small kids) that can wake you up, and you have no control over that.
Don't most people sleep at least 7 hours continuously almost every night?