Conditions that cause fatigue or drowsiness
Many conditions have an effect of creating drowsiness or fatigue in a child. Still others without this effect as a part of their condition, may experience it via medication they may be taking. If it’s desirable to allow the child to nod off, then ensure that they are comfortable and safe. Else if there is a preference toward managing the conditions try some of the following steps.
Take regular breaks and encourage children to stretch.
Ensure that engagement occurs more frequently with the child even if it is not within a turn.
Avoid restricted diet foods that can also include sugary or caffeinated beverages. Because fatigue also can affect concentration, allow for additional time on the childs turn, and encourage/assist with notetaking.
If the need calls for it, you can also shorten session times, group fewer sessions together, and avoid complex Session components.
Much like in the case of if a child experiences increased absence or tardiness, you can provide reading materials, puzzles, and components for home use, so that the child can be working toward the end goals of the group on their own time and in their own environment without the structured limitation of a gameplay environment or make use of some form of free online communication tool (google hangouts, roll20, etc).