Major exchanges 20 and 25 will typically be reached during night / early morning hours, and will contain designated sleeping areas.
Please note that these areas will often be outside, however where possible will be located inside. No one is allowed to sleep on the ground in areas outside of the official sleeping area.
You may wish to look at the route and times you expect to be swapping at major exchanges, and use the time in between to travel to a nearby hotel for a couple of hours rest. Read through the Race Bible and event page on the website to determine the major exchange locations.