Here's my take on it.
Last winter I kept for the first time one small fig tree in my sun room all winter along with some other plants( bay tree, bougainvillea, pineapple, and a meyer lemon which hates it here). When it is extremely cold out (near and below 0 F, it will freeze in the sun room at night so I bring my plants into the house for the night. The fig tree dropped most of it's leaves but held onto 2-3. It didn't have any vegetative growth at all, but it did have some root growth, occasionally a new root would poke out the bottom to the pot. In the winter during the day when it is sunny, we open the doors from the house to the sun room and it heats the house. On a sunny day during the winter from ~10AM-3PM the temperature in the sun room is usually around 70-80 degrees. The cool thing is that the tree in the sun room started active growth only 3-4 weeks before all the dormant trees in the garage began breaking dormancy.
For the past month I have had 7 trees ranging from 2-3 yrs old in the sun room ripening figs. And 4 small trees that were rooted between late winter and late spring. None of these trees are actively growing vegetation. All the bigger trees are gradually yellowing and dropping leaves and slowly going into dormancy while ripening their remaining figs. Most sunny days this time of year it is around 85 degrees in there between 11-2 and that is with at least half of the outer sliding doors opened to cool it. I do put aluminum foil on the sunny side of the pots though, otherwise that side of the pot gets hot enough to kill roots just like during the heat of summer. At night time(now) the temps drop to 40ish in the sun room. During the day when I feel the pots they are cool to the touch. The foil stops the pots from getting hot and warming the soil and roots. Overall, the majority of the time over a 24 hour period the temps are low enough to cool the pots and soil to a degree that they don't get warm enough in the day time to break dormancy or trigger active growth in a tree that isn't quite completely dormant.
Another observation I have is the cuttings I start in late winter. I don't use any artificial light and minimally use a heat mat. As soon as my cuttings are rooted in the cup with green leaves they sit on the floor in front of a sliding glass door that joins to the sun room. Eventually they are acclimated enough to stay in the sun room all day when it is warm enough, but the dry and hot air in the sun room is very hostile to fragile young treelings so I have to be very careful in the beginning. Generally I start several varieties in late winter early spring, and never all at the same time. Without any grow light supplementation and extra warming of the root zone, their growth is very slow for the first couple of months and the plants from cuttings that I start in December won't be much bigger than cuttings that I start a month or more later in late January or February. But it never fails that once day light hours begin to increase, suddenly all the rooted/dry air stable cuttings begin to grow much faster.
What this all means to me is that hours of daylight is one growth trigger, and temperature of the root zone is a stronger trigger for older trees. The small treelings have a relatively warm root zone all along(though not optimal because the floor is cold compared to a 75-80 degree heat mat) and don't grow fast until the daylight hours increase. The potted trees, for me, seem to hold dormancy or not active growth until the root zone is consistently warm enough to meet a threshold.