| Abstract No.: | A-E1166 |
| Country: | Canada |
| | |
| Title: | SLOW-WAVE ACTIVITY DECAY DURING A RECOVERY NIGHT FOLLOWING SLEEP FRAGMENTATION IN DIURNAL TYPES |
| | |
| Authors/Affiliations: | 1 Valérie Mongrain*; 2 Marie Dumont;
1 Douglas Mental Health University Institute; 2 Sacré-Coeur Hospital of Montréal, QC, Canada
|
| | |
| Content: | Introduction: We recently reported, using modeling of slow-wave activity (SWA) decay during a baseline night, that a higher initial level and a steeper decay rate of SWA were associated with an earlier sleep schedule in a subgroup of chronotypes with intermediate circadian phase position. Here, we verify if these differences persist during a recovery night following an increase in sleep pressure.
Methods: Twelve morning types and 12 evening types, selected with the Horne & Östberg questionnaire, were classified according to their circadian phase (salivary Dim Light Melatonin Onset; DLMO): 6 morning and 6 evening types with intermediate phases, and 6 morning and 6 evening types with early or late phases. Four consecutive nights were recorded according to each subject's preferred sleep schedule: a baseline night, two nights of sleep fragmentation (5 minutes of forced wakefulness every half-hour), and a recovery night. SWA (1-5 Hz) was computed by spectral analysis on NREM sleep EEG recorded in the Fz derivation. An exponential decay function was then applied to recovery night relative SWA averaged per sleep cycle.
Results: In subjects with intermediate circadian phases, the initial level of sleep pressure in recovery was higher in morning than in evening types and was correlated with earlier wake time, shorter sleep duration, and a shorter interval between DLMO and wake time (Phase angle; r > -0.61, p < 0.05). However, the decay rate was similar between chronotypes and was not associated with sleep schedule parameters. No difference appeared between chronotypes with extreme phases and no significant correlation was found between individual estimates of SWA decay and sleep schedule.
Conclusions: These results support the assumption that in some individuals, differences in homeostatic regulation are at the origin of morningness-eveningness preference and are directly related to the resulting differences in the phase angle between circadian phase and sleep schedule.
Support: Canadian Institutes of Health Research
|
| | |
| Back |
|
