Sleep duration and brain structure - phenotypic associations and genotypic covariance by Fjell, AM, Sørensen, Ø, Wang, Y, Amlien, IK, Barré, WFC, Bartrés-Faz, D, Bertram, L, Boraxbekk, C-J, Brandmaier, AM, Demuth, I, Drevon, CA, Ebmeier, KP, Ghisletta, P, Kievit, R, Kühn, S, Madsen, KS, Mowinckel, AM, Nyberg, L, Sexton, CE, Solé-Padullés, C, Vidal-Piñero, D, Wagner, G, Watne, LO, Walhovd, KB