The periodograms of the PROBA2/LYRA data show predominant periodicities comparable to the ones observed by other solar time series for the same time range. These periodicities have been found to slightly vary over time. Tracking their evolution on a long-term basis aims at identifying which periodicities are related to each other and at determining which physical processes are at their origin. A study has been made on sunspot area, for which several solar cycles of data exist and for which the periodicities are close to the ones found in LYRA (for the same time range). We used framed Lomb-Scargle periodograms to extract the periodicities and check their evolution. Several significant periodicities behave similarly and seem to be harmonically related.