Shhh, the dolphins need their rest.

Like most animals, dolphins require regular sleep to survive the rigors of their environment.

However, as a recently released study notes, eco-tourists and other human interlopers may be disturbing spinner dolphins’ critical daytime rest periods and driving them out of the few safe habitats they enjoy along Hawaii coastlines.

The study, conducted by scientists at Duke and Stony Brook universities, has yielded what the authors consider a promising new tool to help reduce the negative impact of human disturbance on dolphin rest.

As the authors noted, sleep-deprived dolphins are less able to process information and remain attentive to environmental stimuli. Those chronically deprived of rest are not able to recover, resulting in a loss of ability to forage and detect the presence of predators, and even a loss of ability to produce sounds needed to communicate with other dolphins and to navigate.

Naturally friendly, spinner dolphins in need of rest will leave the safety of a bay and retreat to less protected waters if repeatedly disturbed.

The scientists used geographic coordinates and environmental factors like water depth and calmness, the size and proportions of the bays and the distances from deep-water foraging grounds for hundreds of spinner dolphin sightings between 2000 and 2010.

Researchers focused on 99 bays along the western coastlines of the main Hawaiian Islands, determining that only 21 are suitable for resting dolphins.

"We may be able to minimize detrimental effects on dolphins by putting restrictions or preventative measures into place in a relatively small number of bays, rather than limiting access to dolphins along the entire coast," said lead author Lesley Thorne, of Stony Brook University in New York. "That benefits tourists and tourism operators as well as the dolphins."

Results of the study appear in the online journal PLoS ONE (bit.ly/PMtBGp).