The role of accelerometer-derived sleep traits on glycated haemoglobin and glucose levels: a Mendelian randomization study by Liu, J, Richmond, RC, Anderson, EL, Bowden, J, Barry, CS, Dashti, HS, Daghlas, IS, Lane, JM, Kyle, SD, Vetter, C, Morrison, CL, Jones, SE, Wood, AR, Frayling, TM, Wright, AK, Carr, MJ, Anderson, SG, Emsley, RA, Ray, DW, Weedon, MN, Saxena, R, Rutter, MK, Lawlor, DA