Zoo primates need darkness on day shift

CASE WESTERN (US) — Zoo life can wreak havoc on nocturnal primates. Even something as innocuous as incorrect lighting negatively impacts health and reproduction.

Animals in zoos often have their natural days and nights switched, so they are up and moving when patrons come to see them, not after dark when the zoo is closed.

Studies have shown that human health can suffer, too, when days and nights are switched.

“Shift workers have higher rates of cancer, heart problems, and reproductive problems than the rest of the population,” says Grace Fuller, a doctoral student at Case Western Reserve University.

“Animals have long been used as models for human research,” says Chris Kuhar, curator of Primates and Small Mammals at Cleveland Metroparks Zoo. “Grace is flipping that, using human research to help animals.”

Studies have shown night-shift nurses produce dramatically lower levels of the hormone melatonin, leaving them more susceptible to certain cancers, among other health issues.

Called the hormone of darkness, melatonin in an antioxidant involved in the reproductive cycle and immune system of animals that is secreted by the pineal glad at night, but suppressed in sunlight.

Human health researchers have used the tiny amount of melatonin in spit as a gauge to determine levels of the hormone present in the body, measuring levels nurses produce while working.

For primates including lorises and pottos, their daily shift at the zoo is not as dark as nights in the wild, but is gently lighted to enable patrons to see them.

To determine the effect of the day/night switch, Fuller developed the first assay to study melatonin levels in the spit of zoo primates and has begun to gauge the effects of different wavelenghths and intensities on the animals.

“These primates can navigate through a complicated jungle and avoid predators in the dark.” Fuller says.

Fuller is also observing how active the animals are under red, blue, and white light and measuring melatonin levels in each. The least impactful wavelength can be used to illuminate animals in the future.

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