Nocturnal primates

We’re in the primate house at the Cleveland Metroparks Zoo with researcher Grace Fuller.  She’s heading into the cage of a small nocturnal primate called a potto -  think of a koala with bigger eyes and without the big fuzzy ears

“I’m going to go in and collect from Jizeera.  She’s about six years old, she’s a female potto.  They’re native to sub-Saharan Africa, pretty wide spread throughout that area.”

She's teaching the pottos to chew on a swab in exchange for a meal worm in order to collect the saliva sample.  Fuller will then measure the amount of melatonin in their system.   Melatonin is the principle hormone that tells you what time of day it is.

It’s produced at night deep inside the brain, in the pineal gland, and serves to coordinate the rhythms of all the other hormones that your body produces, reproductive hormones, and stress hormones, all of which vary with time of day.

In a reversal in how science often works, Fuller is using studies done on human shift workers to help nocturnal primates.   She’s basing her work on research done at the Lighting Research Center at Rennselaer Polytechnic Institute in Troy, New York.


Lighting and health effects

Lighting Research Program director Mariana Figueiro studies the health effects of nurses working the night shift.  She says our natural dark and light rhythms become confused when humans are forced to be nocturnal. And that leaves shift workers in a constant state of jet lag.

Figueiro says these nurses actually have high melatonin at night, "but they still may be disrupted because they’re forced to be awake, fight their system at night, try to sleep during the day – so they’re basically jet-lagged, they’re going back and forth to China every week.”

Figueiro says it’s this chronic disruption that impacts the health of shift workers - 

 “With rotating shift workers, 20 – 30 years, and it’s been shown higher risk for breast and colorectal cancer, some studies have shown higher risk for cardiovascular disease, diabetes, and obesity.”

Figueiro says proper lighting can help humans and zoo animals adjust to reversed sleep cycles.

 

Red vs blue lighting

Back in the primate house at the Cleveland zoo, researcher Grace Fuller is testing the effects of lighting on a pair of creatures with huge eyes and human-like hands that look like primate teddy bears -

“So this is a female pygmy slow loris and her house name in the zoo is Hermione, the other pygmy slow loris subject for our study is called Harry and he lives in the exhibit across the way from her.”

Fuller acknowledges someone at the zoo is a Harry Potter fan.  Hermione’s cage is lit with dim blue light, Harry, across the way, has red lighting.   Fuller is testing the melatonin levels in these creatures to determine which best mimics natural darkness.

Fuller says zoos  are using blue and red in sort of equal numbers, but "no one’s really sure what’s best, so that’s one of the factors we want to investigate.  And then we’ll also look at different intensities and brightness of light.”

Primate curator Chris Kuhar says like shift workers, lorises raised in zoos can suffer health effects over their 20 year life span from disrupted light /dark cycles.

He says they are typically dying of cancers, "so while they are living really long lives, there is a potential for light to be a health factor involved.”

Kuhar says unlike human shift workers who must also live in the daylight world, the light cycles of zoo animals can be controlled - “We have the ability to sort of really change their world and make the daytime nighttime for them which is their active period, but we have to control all of the other factors, the light and everything else.  It’s one of the challenges with managing a nocturnal species.”

The study of lighting and health at the Cleveland zoo may in turn help humans whose work-day is night.  Early results show that a portion of the blue spectrum inhibits melatonin production and filtering that color may help maintain healthy hormonal cycles in both human and primate shift workers.