A C172 on an instrument training flight suffered the transitory loss of the directional and attitude gyros while in IMC.

Narrative

After departure and in our initial turn to a 320 heading; ATC asked us where we were going. At this moment we noticed that while in a standard rate turn our directional gyro (DG) was not working. It was frozen and we had actually already done about a 180 [degree turn]. At this point we let them know that we lost our DG and were going to head back to departure airport. In this time period we lost the attitude indicator as well. It was showing a 60 degree bank while we were straight and level. At this point; since we were in hard IMC conditions we declared an emergency to get us back to our departure airport. While enroute; the Controller asked us if we wanted to head to ZZZ where conditions were more favorable; 700 OVC and 7 1/2 visibility. We decided to head to ZZZ and do the GPS [approach]. About 10 minutes from ZZZ the DG and attitude indicator began to function a little better and we landed safely. The part that does not make sense is that we had vacuum pressure. At no point did it show we had no vacuum; but we lost two of the instruments associated with the system. If the conditions had been much better it would not have been as much of an issue. The safest thing at that point was to declare the emergency and make sure we got back on the ground safely.