1. Meditation Research Program, Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School , Boston, MA 02129 , USA
2. Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital , Harvard Medical School, Boston, MA 02129 , USA
3. Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School , Boston, MA 02129 , USA
4. Brainstem Imaging Laboratory, Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School , Boston, MA 02129 , USA
5. Division of Sleep Medicine, Harvard University , Boston, MA 02115 , USA
6. Department of Psychiatry, UMC Utrecht Brain Center, University Medical Center Utrecht , CX Utrecht 3584, the Netherlands
7. Brain Research & Innovation Centre, Ministry of Defence , AA Utrecht 3509, the Netherlands
8. Steiner University College , Oslo 0260 , Norway
9. Department of Psychology and Psychotherapy, Witten/Herdecke University , Witten 58448 , Germany
10. Integrated Curriculum for Anthroposophic Psychology, Witten/Herdecke University , 58448 Witten , Germany