CIRCADIAN DISTRIBUTION OF REST ACTIVITY IN NARCOLEPTIC AND CONTROL DOGS - ASSESSMENT WITH AMBULATORY ACTIVITY MONITORING/

Like human narcoleptics, narcoleptic dogs display cataplexy, fragmente d sleep and excessive daytime sleepiness. Cataplexy in dogs can easily be quantified using a simple behavioural bioassay, the Food Elicited Cataplexy Test. In contrast, daytime sleepiness and fragmented sleep a re more difficult to measure, as long-term, labour-intensive polygraph ic recordings in surgically-implanted animals are needed. In the curre nt study, 24-h rest/activity patterns in genetically narcoleptic, asym ptomatic heterozygous and control Dobermans were compared using small sized ambulatory activity monitoring devices under 12-h light/dark con ditions. Control and ht heterozygous dogs were found to be more active during the light period than during the dark period, thus demonstrati ng a clear 24-h rest/activity cycle. In contrast, narcoleptic dogs wer e relatively inactive during the light period and did not show a clear rest/activity pattern, a result similar to that of human narcoleptics . Considering the fact that narcoleptic dogs show shorter sleep latenc y and sleep significantly more during the daytime than control dogs, t he decrease in activity in narcoleptic dogs during the daytime is most likely a reflection of increased daytime napping in these animals. Am bulatory activity monitoring may be a useful non-invasive method for f uture pharmacological and developmental studies in the narcoleptic can ine model.