Change in diversity over time


I have a sample set whereby I have 32 subjects and 5 samples from each subject over time. I have calculated the Inverse Simpson’s Index for each of these samples. Basically, I want to test statistically if there is a trend over time.

Would it be valid to use tests such as repeated measures ANOVA (assuming that the data is normal) to do so, or can anyone suggest a test that would be more suitable?

Thanks in advance,