By Stephen Beech
Heavy is the head that wears the crown – even for baboons.
Dominant members of primate troops miss out on restful nights, according to a new study.
Researchers found that higher-ranking baboons get less and more fragmented rest at night than their lower-ranked troop mates.
The Swansea University team explained that, in animals that sleep in groups, communal sleeping can offer protection.
But – much like in humans – close neighbors can disturb one another, affecting both the quality and quantity of sleep.
Despite its importance, the social aspect of sleep has rarely been studied in the wild.
Using GPS and accelerometer collars, the research team tracked the daytime and night-time activity of a troop of chacma baboons in South Africa, a species with a strong hierarchical social structure.
Study lead author Marco Fele, a PhD student at Swansea University, said: “We expected dominant baboons to get better rest at night, perhaps because they could choose the most comfortable or sheltered spots.
“But we found the opposite – dominant baboons had less and more interrupted rest.”
The team discovered that baboons are in sync at night, with individuals resting and waking together.
However, because higher-ranked baboons have more nearby group members, that leads them to exert greater influence on each other’s night-time behavior compared to lower-ranked individuals – and so dominant baboons are more likely to wake each other up.
The study, published in Current Biology, is the first to find social hierarchies may impact sleep in wild primates.
It suggests that daytime leadership and influence may come with a night-time cost.
Study co-author Professor Andrew King said: “Just like in humans, sleep is essential for health and decision-making.
“If dominant individuals are resting less at night, it could affect their performance and wellbeing.
Equally, it may be that baboons get enough rest overall, so the costs would be minimal.”
He added: “Future work now needs to test the consequences of these night-time disruptions.”
