How to present cyclic data?

I need to present data across the 24 hours of a day (the daily evolution of the value of a variable). The typical way to display this is a chart (bar, spline, ...) which starts at "00:00" and ends at "24:00" (or variants of).

The data I have is intended to convey the idea that there are variations over a day which are the repeated day after day. This is why I do not want to use an open-ended graph where the extremes are disconnected (the first point and the last one will be the same.

What would be a simple, reasonable way to display this to an end user?

This problem is similar to the classical maps (Mollweide projection for instance), where the Pacific Ocean ends on the right and resumes on the left of the map. In my case the problem is simpler as this is just one variable.