La structure du sommeil et l’activité cardiaque nocturne chez les adolescents ayant un trouble anxieux

The aim of this thesis was to characterize, in a clinical group of children and adolescents with anxiety disorder as a primary diagnostic, the sleep period and to compare it to a control group. Firstly, we have verified if the nocturnal sleep pattern of children and adolescents could be grouped by psychiatric disorders. Sixty-seven children and adolescents with anxiety disorders and nineteen non anxious match controls were monitored using ambulatory recording equipment. Results showed that nocturnal heart rate pattern of anxious adolescents would vary accordingly with the diagnosis. While non anxious adolescents exhibit a flat nocturnal heart rate pattern through the night, anxious participants showed the following associations: a) increased nocturnal heart rate pattern associated with separation anxiety disorder; b) decreased nocturnal heart rate pattern associated with generalized anxiety disorder; and c) U shape nocturnal heart rate pattern associated with social phobia. Moreover, a significant association was found between anxiety diagnosis and presence of morning fatigue. The association between nocturnal heart rate patterns with anxiety suggests that the circadian modulation of heart rate is dysregulated, but what about the sleep macrostructure?  Secondly, we have monitored in a sleep laboratory a clinical sample of nineteen adolescents with pathological anxiety, comorbidity and medication, and compared it to nineteen non anxious match controls. Results showed that anxious participants had longer sleep latency, longer REM sleep latency and longer awake period during sleep when compared to control participants. Compared to control participants, anxious patients subjectively reported sleep disturbances, manifested objective sleep disorders and presented no adaptation to the laboratory environment.  Moreover, higher nocturnal heart rate and higher apnea-hypopnea index were observed in anxious group when compared to non anxious group. Significant positive associations were observed between Trait anxiety and apnea-hypopnea index as well as for sleep latency while manifest anxiety was associated to REM sleep latency. Results suggest that sleep of children and adolescents with pathological anxiety is altered, that signs of physiological hypervigilance are observed and that both are associated.   Following previous results, we have analyzed in a third study heart rate variability during nocturnal sleep using both, times and frequency domains in a clinical sample group of seventeen children and adolescents with anxiety disorder as primary diagnostic with comorbidity and medication. Results showed that anxious when compared to non anxious, had a shorter interbeat interval, and had lower rMSSD values, less high frequency in normalized units and higher low frequency/high frequency ratio. Correlations were observed between clinical anxiety scores and time and frequency domains of heart rate variability. These results add to the growing body of literature that pathological anxiety in a clinical group of children and adolescents impact on sleep process and heart rate regulation during sleep.  Overall findings add to the growing body of recent clinical literature, a sleep alteration description of a clinical sample of children and adolescents. From the three studies of this thesis, results showed that circadian heart rate pattern is altered, that sleep architecture is altered, and that the time and frequency domain of nocturnal heart rate variability is altered in a clinical group of children and adolescents with pathological anxiety.

Keyphrases: Adolescents, Sleep, Children, Anxiety disorder, Adolescents, Heart rate, Heart rate variability