Van den Broek, F. A. R., Klompmaker, H., Bakkere, R. et al. 1995. Gerbils prefer partially darkened cages. Animal Welfare 4, 119-123.

Little is known about housing requirements of gerbils. ... The ten animals included in the [preference] test spent most of their time in the cages that were darkened by 50 and 75 per cent, thus relatively avoiding the standard cage. Preference was mainly determined by visits longer than 15 min and was therefore possibly associated with sleeping behaviour. .... These results imply that gerbils should be housed preferably in cages that allow sheltering in relative dark places. For this purpose, placing shelter objects in the cage should be considered.