A third defeat in a row and only two points from the last 15 mean that there is now a 10-point gap between two teams widely expected to keep each other company through the campaign.
While Sunderland went into first place on the strength of their opportunism and resilience, Bolton are now deep in the swampland of mid-table and unless deficiencies at both ends of the field are addressed will rise little higher.
In the week they sold Nathan Blake to Blackburn - just to rub salt in, he was at the Reebok Stadium as a spectator - Bolton failed to put away any of the string of chances that came their way.
By contrast, Sunderland took advantage of a defence that badly needs a commanding presence to hold it together to score three times from their far less frequent attacks. There is a moral there somewhere.
"I don't think that's the best we've played and I thought Bolton were unfortunate to tell the truth," said Reid, but 3-0 winners can afford to be that generous.
Bolton did put Sunderland under considerable early pressure, something that was reflected in three bookings for rash challenges. One of the perpetrators, Peter Butler, might have considered himself fortunate not to be sent off for bringing down Bob Taylor when he was running in on goal. Reid admitted that his immediate reaction was that his team would be down to 10 men.
Having weathered that, Sunderland caught Bolton on the counterattack. Chris Makin's long ball was won by Niall Quinn, the Wanderers' defence, under pressure from Danny Dichio, failed to clear and Allan Johnston shot in powerfully right-footed.
The defending was even worse when Quinn, who gave Bolton a lesson in feeding off scraps, helped himself to the second. Mark Fish should have cleared Andy Melville's long ball, but got into a tangle, handling the ball and then losing Quinn as he played on and slid it home.
Fish came close to compensating for that howler early in the second half when his header was cleared off the line by Michael Gray. It was one of a series of opportunities for Bolton to get back into the match, but Claus Jensen shot wide, Michael Johansen hit a post from Arnar Gunnlaugsson's clever cross and Per Frandsen also missed the target.
With eight minutes to go, Sunderland completed the punishment. Gray's ball to Quinn was good, the big striker's pull-back was better and the shot on the turn from the substitute, Michael Bridges, went off Keith Branagan's arm and into the top corner.
"I still think they'll be there or thereabouts," said Reid of his old club. "In many ways we were second best today and it takes a good side to do that to us. But with the players we have out we showed great strength and character."
It is on those qualities that unbeaten runs and successful promotion campaigns are built.
Bolton's manager, Colin Todd, denied having subjected his players to a post-match grilling despite taking an hour to emerge for the conference.
"Football is about winning games," Todd said. "At the moment we're just not getting the luck, it's not going for us. For the first 25 minutes we played really well but couldn't get a break. I was pleased with the manner in which we tried to get back into the game in the second half but you need a little bit of luck and we didn't get it.
"I'm disappointed but we've got to bounce back. When the chips are down the character has to come through in individuals. There's no magic formula. Just dig in deep."
Goals: Johnston (27) 0-1; Quinn (34) 0-2; Bridges 83 (0-3).
Bolton Wanderers (4-4-2): Branagan; Bergsson, Todd, Fish (Aljofree, 71), Phillips; Johansen (Holdsworth, 71), Jensen, Frandsen, Elliott; Taylor, Gunnlaugsson. Substitutes not used: Jaaskelainen.
Sunderland (4-4-2): Sorensen; Makin, Butler, Melville, Gray; Mullin, Ball, Thirlwell (Williams, 81), Johnston; Quinn (Scott, 83), Dichio (Bridges, 63).
Referee: B Knight (Orpington).
Bookings: Bolton: Elliott, Todd. Sunderland: Makin, Ball, Butler, Mullin.
Man of the match: Melville.
Attendance: 21,676.Reuse content