* a current or past history of bipolar disorder, schizophrenia, neurodevelopmental disorder, organic mental disorder; intellectual disabilities or substance use disorder. * presence of contraindications to bright light therapy: for example, history of light induced migraine/ epilepsy; current use of photosensitizing medications; presence of eye disease: e.g. retinal blindness, severe cataract, glaucoma. * significant medical condition/ hearing impairment/ speech deficit leading to incapability of completing clinical interview. * regular shift-workers * trans-meridian flight in the past 3 months and during the study * currently receiving any structured psychotherapy * self-reported untreated sleep disorders (e.g. severe insomnia, obstructive sleep apnea, restless leg syndrome), psychiatric illness (e.g. depression), or medical conditions associated with fatigue (e.g. anemia, heart failure, autoimmune disorders) * enrolment in another clinical trial of an investigational medicinal product or device.

* a current or past history of bipolar disorder, schizophrenia, neurodevelopmental disorder, organic mental disorder; intellectual disabilities or substance use disorder. * presence of contraindications to bright light therapy: for example, history of light induced migraine/ epilepsy; current use of photosensitizing medications; presence of eye disease: e.g. retinal blindness, severe cataract, glaucoma. * significant medical condition/ hearing impairment/ speech deficit leading to incapability of completing clinical interview. * regular shift-workers * trans-meridian flight in the past 3 months and during the study * currently receiving any structured psychotherapy * self-reported untreated sleep disorders (e.g. severe insomnia, obstructive sleep apnea, restless leg syndrome), psychiatric illness (e.g. depression), or medical conditions associated with fatigue (e.g. anemia, heart failure, autoimmune disorders) * enrolment in another clinical trial of an investigational medicinal product or device.

a current or past history of bipolar disorder, schizophrenia, neurodevelopmental disorder, organic mental disorder; intellectual disabilities or substance use disorder. presence of contraindications to bright light therapy: for example, history of light induced migraine/ epilepsy; current use of photosensitizing medications; presence of eye disease: e.g. retinal blindness, severe cataract, glaucoma. significant medical condition/ hearing impairment/ speech deficit leading to incapability of completing clinical interview. regular shift-workers trans-meridian flight in the past 3 months and during the study currently receiving any structured psychotherapy self-reported untreated sleep disorders (e.g. severe insomnia, obstructive sleep apnea, restless leg syndrome), psychiatric illness (e.g. depression), or medical conditions associated with fatigue (e.g. anemia, heart failure, autoimmune disorders) enrolment in another clinical trial of an investigational medicinal product or device.

a current or past history of bipolar disorder, schizophrenia, neurodevelopmental disorder, organic mental disorder; intellectual disabilities or substance use disorder. presence of contraindications to bright light therapy: for example, history of light induced migraine/ epilepsy; current use of photosensitizing medications; presence of eye disease: e.g. retinal blindness, severe cataract, glaucoma. significant medical condition/ hearing impairment/ speech deficit leading to incapability of completing clinical interview. regular shift-workers trans-meridian flight in the past 3 months and during the study currently receiving any structured psychotherapy self-reported untreated sleep disorders (e.g. severe insomnia, obstructive sleep apnea, restless leg syndrome), psychiatric illness (e.g. depression), or medical conditions associated with fatigue (e.g. anemia, heart failure, autoimmune disorders) enrolment in another clinical trial of an investigational medicinal product or device.