Sleep and circadian rhythms in health and disease: a complex interplay

Fil: Zaki, Nevin F. W. Mansoura University. Faculty of Medicine. Department of Psychiatry. Sleep Research Unit; Egipto Fil: Spence, David Warren. Investigador Independiente; Canada Fil: BaHammam, Ahmed S. King Saud University. College of Medicine. University Sleep Disorders Center; Arabia Saudita Fil: Pandi Perumal, Seithikurippu R. Somnogen Canada Inc.; Canada Fil: Cardinali, Daniel Pedro. Pontificia Universidad Católica Argentina. Facultad de Ciencias Médicas. Instituto de Investigaciones Biomédicas; Argentina Fil: Cardinali, Daniel Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Brown, Gregory M. University of Toronto. Centre for Addiction and Mental Health. Department of Psychiatry; Canada Abstract: We read with interest the letter to editor by Bernstein et al. [1], in response to our recently published paper [12]. Unfortunately, Bernstein et al. [1] mistakenly assumed that our literature search did not provide appropriate citations. They also state that we failed to mention the already existing literature on circadian and seasonal changes of the suprachiasmatic nucleus (SCN) in mentally health and in disease. Their comments concern a particular reference to alterations of the chemical composition of this nucleus in depression in humans. In particular, they complain that the significant contributions of Bernstein and colleagues and Swaab and colleagues (referenced elsewhere, Bernstein et al. [1]) were not cited in our paper.