When my sons get like this I have a check list
Sleep, nutrition, exercise (significant), brain work, personal goals, contribution/responsibility to family life, fun time/one on one time with either parent
If I have been or kids have been slacking in one or more of these areas we work on fixing it.
We might teach them a new household chore and make them responsible or find a new goal for them to work on achieving or study a topic that they are interested in like hurricanes or a person from history.
Also I have in the past required the hour after lunch to be quite time for the entire house no electronics ( other than soft music) reading, napping, writing, in your own space...because we are all home during the summer and we all need alone time.
