Inside Dolphin Academy’s Multi-Year Sleep Research: What We’ve Learned Since 2013

Curious how dolphins sleep with part of their brain awake? Since 2013, the Dolphin Academy sleep research program has been quietly answering that question through non-invasive, around-the-clock observations in Curaçao. In this overview, you’ll learn how long-term, 24/7 studies reveal each dolphin’s rest preferences, what makes mother–calf rhythms unique, how circadian timing is tested, and why these insights matter for dolphin welfare and education.

A 24/7 approach that began in 2013

In January 2013, Dolphin Academy (DA/UG) launched a multi-year project focused on "sleep-like resting behavior."

• Researchers conduct non-invasive, around-the-clock observations.
• Field sessions are scheduled annually at the end of the rainy season (end of February, beginning of March), building toward a full 24/7 picture of daily patterns.
• The program documents how dolphins spend their days and nights across life stages.

What the ongoing dataset captures

Over the years, the team has compiled a life-long dataset of daily rhythms within the dolphin community, including:

• How infant dolphins allocate their time immediately after birth and as they become semi-independent calves.
• Activity range as they grow into adolescence.
• Contributing factors that shape daily rhythms in adulthood.
• Individual sleep preferences: how much time each dolphin prefers to sleep, preferred locations, and preferred associates.

By combining data across age groups over time, researchers monitor trends in rhythmic variation, differences between males and females, and how being a full-time mother influences rest/wake patterns.

Why dolphin sleep looks different

Dolphins have evolved unihemispheric "sleep," allowing one hemisphere of the brain to rest while the other stays awake. This adaptation supports vital functions—like surfacing to breathe and remaining attentive to the environment—while still providing periods of rest. Dolphin Academy has reproduced electroencephalogram (EEG) testing to establish a baseline for its population, supporting a multi-year program that spans:

• Rest/wake cycles from birth to maturity
• Sensory responsiveness during resting
• Time–place association and anticipatory behavior
• Hormone sampling and measurement using saliva and blow-hole chuffs

This blend of continuous observation and targeted assessments offers a structured view of rest that can be compared across individuals and life stages.

Mother–calf behavior: Rest that changes with age

A key focus of the long-term study is the development of rest/wake behavior before and after birth for mother dolphins and their newborn calves. Dolphins are among the few mammals that remain in constant movement after birth. As a result, calves may sleep very little in the first days and even weeks. Unlike most mammals—where babies sleep more than adults—dolphin calves increase their sleep with age. This stands in contrast to humans, who generally sleep less as they grow older.

Each new birth adds valuable data points to understand how early-life activity and maternal responsibilities shape long-term rhythms.

Do dolphins “sleep deeply”? Testing sensory responsiveness

What is an arousal threshold?

In sleep science, an increased arousal threshold (decreased sensory responsiveness) means it’s harder to wake an individual from deeper sleep. Humans, for example, cycle through sleep stages in which responsiveness changes.

The question for dolphins

Because dolphins maintain activity in part of the brain during rest, researchers are investigating whether they show an increased arousal threshold at all. Do resting dolphins respond like fully awake dolphins, or is there a measurable change in responsiveness?

Dolphin Academy is in the last stages of testing arousal thresholds by broadcasting different frequencies and volumes of sounds through an underwater speaker while dolphins exhibit resting behavior. These tests help clarify how "deep" rest might look in a species that never fully shuts down both hemispheres at once.

Time–place association: Evidence for circadian timing

What is a circadian rhythm?

A circadian rhythm is an internal 24-hour clock that organizes behavior—such as feeding and resting—at certain times of day.

How it’s tested at Dolphin Academy

To identify circadian timing, the team evaluates anticipatory behavior: a food-based reward is presented at specific locations and times. If a functioning circadian clock is present, dolphins should begin showing predictable activity before scheduled events.

• Preliminary results indicate differences between males and females—and, more specifically, females with calves.
• These findings are based on a small number of dolphins with varying results, so further testing is needed.

This method connects observable behavior (anticipation) to internal timing, enriching the broader picture of daily rest and activity cycles.

From long-term data to everyday care

Long-running, non-invasive studies support a detailed understanding of each dolphin’s preferences and rhythms. In practice, insights like preferred resting locations, social associations, and timing patterns can inform daily management and enrichment in ways that respect individual needs. A clearer view of rest/wake cycles across life stages also supports thoughtful educational storytelling and hands-on learning—core to Dolphin Academy’s approach in Curaçao.

• The Academy’s broader initiatives—such as Dolphin Health Care and Open Sea Training—complement research efforts by prioritizing natural behaviors and well-being.
• Visitors can deepen their understanding through experiences like Dolphin Encounter, Dolphin Swim, Dolphin Snorkel, and Open Water Dolphin Dive, which connect education with meaningful interaction.

While the research continues, the framework already links science, care, and education in a cohesive way.

Quick answers about Dolphin Academy sleep research

When did the program start?

• January 2013.

How are observations conducted?

• Non-invasive, around-the-clock sessions held annually at the end of the rainy season, building toward a full 24/7 profile of daily patterns.

Do dolphins sleep like humans?

• No. Dolphins exhibit unihemispheric sleep—one hemisphere rests while the other stays awake—unlike human bilateral sleep.

Do calves sleep more than adults?

• Early on, calves may sleep very little; their sleep increases with age, a pattern opposite to humans.

How is sensory responsiveness tested?

• By broadcasting sounds at different frequencies and volumes through an underwater speaker while dolphins are resting.

How is circadian timing assessed?

• Through time–place association tests that measure anticipatory behavior before scheduled, food-based rewards at specific locations.

What else is measured?

• EEG baselines for resting brain activity and hormone sampling using saliva and blow-hole chuffs support the multi-year research program.

Practical takeaways and tips

• For learners: Use the concepts of unihemispheric sleep and circadian rhythms to frame how dolphins balance vigilance with rest. Contrast calves’ increasing sleep over time with human development to anchor understanding.
• For educators: Build lessons around observable behaviors—anticipation before scheduled events, preferred resting spots, and social associations—so students connect abstract physiology with real-world patterns.
• For visitors: Choose an experience that matches your comfort in the water—Dolphin Encounter (waist-deep platform), Dolphin Swim, Dolphin Snorkel, or Open Water Dolphin Dive—to see natural behaviors discussed in research come to life.
• For ongoing curiosity: Explore the Dolphin Research and Dolphin Health Care sections to follow how multi-year data informs care and public education.

Conclusion: Science, care, and connection—over years, not moments

Dolphin Academy’s multi-year sleep research demonstrates the value of patient, 24/7 observation. Since 2013, the program has documented individual rest preferences, mother–calf dynamics, and the timing mechanisms that organize daily life. With EEG baselines, sensory responsiveness tests, time–place association assessments, and hormone sampling, the work continues to deepen our understanding of how dolphins rest—and thrive.

Ready to learn more or see these behaviors up close? Explore Dolphin Research and Dolphin Health Care, then book a Dolphin Encounter, Dolphin Swim, Dolphin Snorkel, or Open Water Dolphin Dive to connect research with real-world experience.