I'm getting too old now for medium roasts in the morning.....
Light-roasted beans actually contain (or CAN contain) more caffeine…as they are roasted at a lower temp and sometimes shorter duration. Many factors, of course, but ultimately “light” does not mean “light on the caffeine”. I learned this while our one daughter spent a few years working at different coffee shops…after getting her 2 degrees ;) (yes, she finally got a job using those degrees!)