Diki is correct in that running in the morning before breakfast would be the preferred way. It will do two things, kickstart your metabolism for the day, and help your muscles recover more effeciantly. Night time is when your body does its "maintenance". Flushing organs and such. If you excercise to close to bed time this will cause your body to focus on your muscles and not the regular maintenance cycle of the body and can cause you not to be able to flush toxins and infections as well as you should. The other thing that running in the evenings does is cause the body not to get a full rest at night since the normal activity level has increased and different chemicles are released in the blood stream and the brain. If you are running within 3-4 hours before bed time, you may want to go to bed earlier and run in the mornings if that is an option. If you are not sleeping well at night I would DEFINATELY change the routine.
If you must run in the evenings, have a small portion of an easily digestable protein, followed with a potasium rich snack 20-30 min afterwards. The former will give you a bit more energy, and the latter will help with reconstruction of muscle tissue. Hopefully both will lead to a greater amount of sleep and a better muscle tone.
But, do what you enjoy, most importantly. If running at night keeps you going, and you find it difficult to get out in the morning, then keep it up. Don't stop.