Are you a back or side sleeper? For those of you who think there is such a thing as a ‘side’ sleep or a ‘back’ sleeper, how do you explain that “30% of the cohort incorrectly reported their body position at the time of lights-out, suggesting that uncertainty exists even when recollecting position while awake.” And “Our results suggest that self-reported body position may not reliably match objective position” Russo, K. and Bianchi, M.T., 2016. How reliable is self-reported body position during sleep?. Journal of Clinical Sleep Medicine, 12(01), pp.127-128 here. Or the data presented in this paper De Koninck, J., Lorrain, D. and Gagnon, P., 1992. Sleep positions and position shifts in five age groups: an ontogenetic picture. Sleep, 15(2), pp.143-149 here or this paper Dzvonik, M.L., Kripke, D.F., Klauber, M. and Ancoli-Israel, S., 1986. Body position changes and periodic movements in sleep. Sleep, 9(4), pp.484-491 here. For those who find science a bit of a challenge see the wonderful photos no. 45 (below) and no.37 by Paul Marie Schneggenburger for proof here There is no such thing as a front sleeper, a side sleeper or a back sleeper, there are only individual sleepers.