EssaySleep, sleep timing and chronotype in animal behaviour
Section snippets
Chronotype as a Personality Aspect
Sleep timing or chronotype has been described as an interesting aspect of personality (Matthews, 1988). The term ‘personality’ was first used for humans, but animal personality is also an increasing field of study, with articles by Gosling and John (1999) and Gosling, Kwan, and John (2003) being an important starting point. The first reviews (e.g. Réale, Reader, Sol, McDougall, & Dingemanse, 2007) labelled these personality aspects as temperament, a definition paralleled, for example, by
Chronotype in animals
In laboratory animals, there is some evidence for the existence of chronotypes (Aschoff and Wever, 1962a, Labyak et al., 1997, Wicht et al., 2014). For example, Aschoff and Wever (1962a) reported individual differences in chaffinches, Fringilla coelebs. Labyak et al. (1997) examined 15 variables of circadian activity and temperature for diurnal degus, Octodon degus: they noted similar chronotype variations as described for humans with extreme individuals differing by one or more standard
Physiological aspects
In nonhuman animals, chronotype has not yet been studied extensively in relation to hormone measures or other physiological measures in field studies. However, there is some evidence for such relationships from humans, both men and women from laboratory and field settings. First, body temperature was lower at night and the lowest core body temperature (the point of lowest temperature) was earlier in the night in morning than in evening types, both in the laboratory (Baehr, Revelle, & Eastman,
Ontogenetic aspects and sex differences
Ontogenetic aspects have been discussed in detail for humans, and it has been found that there are two significant changes in sleep–wake behaviour during adolescence (Roenneberg et al., 2004). First, with the onset of puberty, children very quickly become evening oriented around the age of 12–14 years (Carskadon et al., 1998, Randler, 2011). This has been supposed to be related to pubertal changes in hormone secretion, although this idea has not been convincingly tested. Second, at the end of
External abiotic environmental influence
Large seasonal differences in sleep timing of 4.8 h between summer and winter have been found in blue tits, and these differences are much larger than in humans. In humans at around 69° latitude in Norway (Tromsø), the difference was only some 8 min which was an unexpected result (see Johnsen, Wynn, Allebrandt, & Bratlid, 2013). A similar effect as in the blue tits was expected (but with a weaker difference of 30 min or 1 h). Environmental factors determining sleep–wake patterns could be
Sexual selection and mating
The sex differences in sleep–wake variables in the blue tit were considered as an effect of sexual selection, similarly to humans (Randler et al., 2012a). Blue tit males that ‘went out of bed’ earlier had a higher mating success (Poesel, Kunc, Foerster, Johnsen, & Kempenaers, 2006). This is supported by Helm and Visser (2010) who reported that the shorter free-running period length (shorter than 24 h in dim light) may be a consequence of sexual selection. Offspring from extrapair matings had
Correlates and evolutionary consequences
Health-related aspects have been revealed in relation to chronotype and sleep duration in different studies in humans (e.g. Lázár et al., 2012), late risers having worse health. For example, being overweight or obese has been linked with evening orientation and increased stress hormones (Lucassen et al., 2013) or generally an unhealthy diet (Kanerva et al., 2012). Also, health problems have been found with eveningness: there was a predisposition in evening types to type 2 diabetes, while
Conclusions and further topics
What can psychologists learn from animal studies on sleep behaviour? Animals are less restricted or influenced by social schedules (e.g. work or school in humans) and the comparison of results from animals and humans may help researchers assess social aspects of sleep behaviour and their importance for the circadian rhythm. More social animals, such as baboons or meerkats, might have higher synchronization in their sleep–wake behaviour than solitary species. What can be learnt from studies on
Acknowledgments
I am grateful to Ana Sendova-Franks for her encouragement, and I am specifically thankful to the three referees with their views helping to clarify the logic of this essay.
References (63)
Temperament and personality
Current Biology
(1994)- et al.
The stability of the morning affect scale across age and gender
Personality and Individual Differences
(2013) - et al.
Repeatability and heritability of exploratory behaviour in great tits from the wild
Animal Behaviour
(2002) - et al.
Adolescent sleep patterns in humans and laboratory animals
Hormones and Behavior
(2013) - et al.
Lack of major seasonal variations in self -reported sleep-wake rhythms and chronotypes among middle aged and older people at 69 degrees North: the Tromsø Study
Sleep Medicine
(2013) - et al.
Artificial night lighting affects dawn song, extra-pair siring success, and lay date in songbirds
Current Biology
(2010) - et al.
Early birds are sexy: male age, dawn song and extrapair paternity in blue tits, Cyanistes (formerly Parus) caeruleus
Animal Behaviour
(2006) - et al.
Eveningness is related to men's mating success
Personality and Individual Differences
(2012) - et al.
Chronotype but not sleep length is related to salivary testosterone in young adult men
Psychoneuroendocrinology
(2012) - et al.
Morningness-eveningness, habitual sleep-wake variables and cortisol levels
Biological Psychology
(2010)
Epidemiology of the human circadian clock
Sleep Medicine Review
Circadian rhythm of wrist temperature in normal-living subjects: a candidate of new index of the circadian system
Physiology & Behavior
Variation in sleep behaviour in free-living blue tits, Cyanistes caeruleus: effects of sex, age and environment
Animal Behaviour
Circadian typology: a comprehensive review
Chronobiology International
Über Phasenbeziehungen zwischen biologischer Tagesperiodik und Zeitgeberperiodik
Zeitschrift für vergleichende Physiologie
Beginn und Ende der täglichen Aktivität freilebender Vögel
Journal of Ornithology
Individual differences in the phase and amplitude of the human circadian temperature rhythm: with an emphasis on morningness-eveningness
Journal of Sleep Research
Sleep-wake cycle of adolescents in Côte d'Ivoire: influence of age, gender, religion and occupation
Chronobiology International
Individual differences in the amount and timing of salivary melatonin secretion
PLoS One
Sex differences in phase angle of entrainment and melatonin amplitude in humans
Journal of Biological Rhythms
Adolescent sleep patterns, circadian timing, and sleepiness as a transition to early school days
Sleep
Sex differences in the circadian control of hamster wheel-running activity
American Journal of Physiology – Regulatory, Integrative and Comparative Physiology
Reviewing the psychometric properties of contemporary circadian typology measures
Chronobiology International
Individual-based measurements of light intensity provide new insights into the effects of artificial light at night on daily rhythms of urban-dwelling songbirds
Journal of Animal Ecology
Clocks for the city: circadian differences between forest and city songbirds
Proceedings of the Royal Society B: Biological Sciences
Artificial light at night advances avian reproductive physiology
Proceedings of the Royal Society B: Biological Sciences
Sex difference in the near-24-hour intrinsic period of the human circadian timing system
Proceedings of the National Academy of Science
The biological basis of personality (no. 689)
Personality dimensions in nonhuman animals: a cross-species review
Current Directions in Psychological Science
A dog's got personality: a cross-species comparative approach to evaluating personality judgments
Journal of Personality and Social Psychology
Adolescent changes in the homeostatic and circadian regulation of sleep
Developmental Neuroscience
Cited by (40)
Female chronotype and aggression covary on different hierarchical levels in a songbird
2024, Animal BehaviourResearch on spatiotemporal variation characteristics of soundscapes in a newly established suburban forest park
2022, Urban Forestry and Urban GreeningCitation Excerpt :Previous studies on the relationship between acoustic indices and biodiversity mostly focused on the breeding season, when birdsongs contribute significantly to biophony (Wheeldon et al., 2019; Bradfer-Lawrence et al., 2020; Barbaro et al., 2022), and this study complemented the pattern of acoustic activity by providing data from the non-breeding season. Temperature, sunrise, sunset, or artificial light may affect birds' dawn chorus time (Arroyo-Solís et al., 2013; Randler, 2014). We found that the peak of dawn acoustic activity in this study occurred approximately one hour later in winter than in the warmer seasons.
Social sleepers: The effects of social status on sleep in terrestrial mammals
2022, Hormones and BehaviorCitation Excerpt :In most mammals and birds, sleep is a dynamic process with two different phases: rapid eye movement (REM) sleep and non-REM (NREM) sleep (Aserinsky and Kleitman, 1955; Jouvet and Mounier, 1960). There is evidence from various species that sleep architecture (the distribution of NREM and REM across a sleep bout) and intensity (sleep depth) vary widely across populations and individuals (Randler, 2014; Rattenborg et al., 2017). Social status within a group may predict when an animal sleeps, where they sleep, who they sleep with, and how well they sleep (Fig. 1).
How environmental conditions affect sleep? An investigation in domestic dogs (Canis lupus familiaris)
2022, Behavioural ProcessesCitation Excerpt :Behavioural activity patterns fluctuate across 24 h (i.e., circadian rhythms), in a process modulated by external triggers (e.g., light levels and temperature), which generate appropriate endogenous responses to ensure adaptation (Adan et al., 2012; Morgan, 2004; Randler, 2014). Similar to the circadian rhythm, sleep also has an adaptative function: being inactive and unconscious is advantageous since sleep helps maintain homeostasis (Mader and Mader, 2016; Randler, 2014; Roth et al., 2010). Sleeping patterns have mostly been investigated in animals under controlled laboratory conditions, without the full consideration of their ecological value and without considering the importance that different ecological variables may have on sleep quality (Aulsebrook et al., 2016; Tougeron and Abram, 2017).
Plasticity and repeatability of activity patterns in free-living Arctic ground squirrels
2020, Animal BehaviourCitation Excerpt :Some individuals may consistently begin and end activity earlier in the day than others; these persistent individual differences in activity timing are called chronotypes. Chronotypes were first described in humans (summarized in Randler, 2014), then in laboratory animals (e.g. Labyak, Lee, & Goel, 1997), and only more recently in free-living systems. Chronotype studies in free-living animals are still relatively rare and are almost exclusively conducted in birds.