What happens to the level of national income when aggregate demand falls short of aggregate supply?

When aggregate demand falls short of aggregate supply, there is an imbalance in the economy that can lead to a decrease in national income. This is because when there is excess supply and not enough demand, businesses may reduce production and lay off workers, leading to a decrease in overall economic activity and income. This can result in a decrease in GDP, lower levels of employment, and potentially a recession if the imbalance persists.