Your guests’ energy levels can really effect the atmosphere of a wedding. The timings are important to this in terms of how energised they are at different points of the day.
If they have been stood for 2 hours during a drinks reception, their energy levels are likely to have dipped as they might be feeling hungry with achy feet. Or if they have been sitting, eating and drinking for a few hours, the energy might have naturally mellowed out. If you want to overall atmosphere to change you can use music, or lighting and get people moving before the next part of your day officially starts.
I am known for proactively using the time between the wedding breakfast and the dancing to naturally create a more upbeat atmosphere. This means that once the band start, everyone is itching to get on the dance floor! Thinking about your timings and how your guests may be feeling will make a big difference to your wedding day.