convert axis label from seconds to date

I'm plotting data based on samples every second. For example I have a plot over 5 days (5 days equals 5*24*60*60 = 432000 seconds) and therefore 432000 values. I don't have an explicit time vector, so I'm plotting the data using the command plot(y_data). So the x axis shows the indices, which represents the time stamp in seconds as well.

What I'm struggling with now is to convert the x axis to a date format. I want it to be something like 'Monday 19:25' or maybe 'Monday 3rd April 2009' or whatever date format datestr supports.

I wasn't able to figure out a way how to do that.

Thanks for your help!