Sleep disturbances are common in patients with schizophrenia. Mice lacking the cytoskeletal-associated protein Stable Tubule Only Polypeptide (STOP) display cognitive, behavioural and neurobiological deficits that mimic those seen in schizophrenia, but there is little evidence of sleep changes in these mice. To investigate their sleep patterns, electroencephalogram (EEG) and electromyogram were recorded under a 12:12 light:dark cycle in adult male STOP-null (KO; n=7) and wild-type (WT; n=8) mice, during a 24 h baseline period, followed by 6 h of sleep deprivation, and a 24 h recovery period. In the baseline period, KO mice spent more time awake and less time in non-rapid eye movement (NREM) and REM sleep compared to WT mice. Particularly in the dark phase, KO mice had more wake and NREM sleep episodes, and shorter NREM and REM sleep episodes relative to WT mice. Following sleep deprivation, during the first 12 h of recovery (i.e. dark phase), both groups showed similar increases in NREM and REM sleep amounts and NREM EEG delta power relative to corresponding baseline periods. These findings indicate that the STOP-null mice sleep less and their sleep is more fragmented compared to WT mice. These features are consistent with the sleep abnormalities found in individuals with schizophrenia.

La lumière influence fortement la physiologie et le comportement en exerçant des effets non-visuels de deux types : i) indirects, via la resynchronisation de l’horloge centrale qui est située dans les noyaux suprachiasmatiques (NSC), ii) directs, indépendants du processus circadien, via des mécanismes encore mal compris. Nos travaux chez la souris ont montré que l’influence directe de la lumière constitue un mécanisme majeur de régulation du sommeil, de l’éveil et de l’humeur, au même titre que le processus circadien. Ces effets sont majoritairement médiés par la mélanopsine, un photopigment exprimé dans la rétine, et relayés au niveau cérébral par différentes structures comme les NSCs et le VLPO. Ainsi, le rôle des NSCs ne doit pas être interprété qu’au travers de leur fonction d’horloge. Ensuite, dans une perspective de recherche translationnelle de l’animal à l’homme, nous avons validé Arvicanthis ansorgei, comme modèle d’étude du sommeil afin de pouvoir interpréter nos résultats chez un rongeur diurne. Enfin, de nombreuses données suggérant que les effets directs de la lumière modulent l’activité du système dopaminergique, nous avons évalué l’intérêt de la luminothérapie dans des pathologies dopaminergiques (maladie de Parkinson, syndrome des jambes sans repos, troubles de l’humeur). Ces avancées ouvrent de nombreuses perspectives pour une meilleure utilisation de la lumière dans notre société ainsi qu’en pathologie. / Light influences physiology and behavior through both types of non-image-forming effects: i) indirect, synchronizing the circadian master clock located in the suprachiasmatic nucleus (SCN), ii) direct effects, independent from the circadian process though mechanisms poorly understood. Our studies in mice demonstrate that the direct influence of light constitutes a key mechanism of regulation for sleep, alertness and mood and is as important as the circadian process. The direct effects of light are mainly mediated through melanopsin, a retinal photopigment that projects to the different structures of the brain such as the SCN and the VLPO. The SCN, beyond their role as circadian clock are also a relay system for the direct effects of light. Further, we validated Arvicanthis ansorgei as a diurnal model for the study of sleep regulatory mechanisms. This is an important step in the translational approach from animal research to applications in humans. Various data suggest that the direct effects of light interact with the dopaminergic system. In the last part of this thesis, we evaluated the indication of bright light therapy in dopaminergic pathologies (Parkinson disease, restless legs syndrome, mood disorders). These advances open up new perspectives for possible applications of light therapy and may help improving societal lightening conditions.