Photochromic devices are ones which change colour upon the irradiation of light. These devices can be used a sensors, logic gates and privacy windows etc. Here we show and example of a hydrogel that undergoes a reversible change from transparent to a dark brown colour upon the irradiation with UV light. An important feature of these hydrogels is that they do not fall apart upon multiple cycles of this irradiation, and whether the gel network has changed upon irradiation. So far we have studied this using rheology. The irradiated gels differ from the non-irradiated gels by a change in breakdown, telling us the bulk sample has changed. We will use SANS to probe the network changes in more detail, to see whether the fibre morphology has changed, or whether it is a bulk network change. We can also see how reversible this change is on the different levels of organization of the gel network.