1. Wits Sleep Laboratory, Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa;
2. Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy;
3. Division of Physiological Sciences & Health through Physical Activity, Lifestyle and Sport Research Centre, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa;
4. Feinberg School of Medicine, Northwestern University, Chicago, Illinois;
5. Northumbria Centre for Sleep Research, Department of Psychology, Northumbria University, Newcastle-upon-Tyne, United Kingdom;
6. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa