Journal of Sleep Research, 2020;00:e12998.  First published: 17 February 2020,  Free full-text  DOI: 10.1111/jsr.12998

Vivien Reicher1, Anna Kis2, Péter Simor3,4, Róbert Bódizs4, Ferenc Gombos5,6, Márta Gácsi1,7

1 Department of Ethology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
2 Research Centre for Natural Sciences, Institute of Cognitive Neuroscience and Psychology, Budapest, Hungary
3 Institute of Psychology, Eötvös Loránd University, Budapest, Hungary
4 Institute of Behavioural Sciences, Semmelweis University, Budapest, Hungary
5 Department of General Psychology, Pázmány Péter Catholic University, Budapest, Hungary
6 MTA‐PPKE Adolescent Development Research Group, Budapest, Hungary
7 MTA‐ELTE Comparative Ethology Research Group, Budapest, Hungary


The importance of dogs (Canis familiaris) in sleep research is primarily based on their comparability with humans. In spite of numerous differences, dogs’ comparable sleep pattern, as well as several phenotypic similarities on both the behavioural and neural levels, make this species a most feasible model in many respects. Our aim was to investigate whether the so‐called first‐night effect, which in humans manifests as a marked macrostructure difference between the first and second sleep occasions, can be observed in family dogs. We used a non‐invasive polysomnographic method to monitor and compare the characteristics of dogs’ (N = 24) 3‐hr‐long afternoon naps on three occasions at the same location. We analysed how sleep macrostructure variables differed between the first, second and third occasions, considering also the effects of potential confounding variables such as the dogs’ age and sleeping habits. Our findings indicate that first‐night effect is present in dogs’ sleep architecture, although its specifics somewhat deviate from the pattern observed in humans. Sleep macrostructure differences were mostly found between occasions 1 and 3; dogs slept more, had less wake after the first drowsiness episode, and reached drowsiness sleep earlier on occasion 3. Dogs, which had been reported to sleep rarely not at home, had an earlier non‐rapid eye movement sleep, a shorter rapid eye movement sleep latency, and spent more time in rapid eye movement sleep on occasion 3, compared with occasion 1. Extending prior dog sleep data, these results help increase the validity of further sleep electroencephalography investigations in dogs.