A blockhead needs energy to carry out its tasks, measured on its energy bar.
Since version 1.4, a blockhead who has finished sleeping in a bed or drinking coffee will have its energy bar temporarily colored gold (yellow) to indicate that it hasn't begun diminishing. It is normally green for the filled portion.
As a blockhead's energy decreases, its actions slow down. When the energy bar is completely empty the blockhead can still operate, albeit at a much reduced rate.
Starting in version 1.2, a blockhead that has worked long enough with an empty energy bar that their happiness bar also becomes empty will stop, displaying the message "TOO TIRED TO WORK" in the task window. If a blockhead goes long enough with a completely depleted energy bar, it may "collapse from exhaustion" and fall asleep wherever it is.
An energy bar is always slowly decreasing, although certain actions may reduce it faster.
When a blockhead's energy bar is low enough, its happiness will also decrease.
Energy will not decrease during meditation.
Sleep restores energy faster if done using a bed, with improved beds acting faster and having longer-lasting results.
Coffee and coffee cherries must be consumed to work. Selecting the item presents an "Eat" button over the blockhead which will cause one count to be consumed per tap and go away when there is a tap anywhere else. Coffee will completely restore even a fully depleted energy bar. Coffee cherries restore only a small portion of the energy bar.