Abnormal behavioral episodes associated with sleep and quiescence in Octopus insularis : Possible nightmares in a cephalopod?
Eric Angel Ramos, Mariam Steinblatt, Rachel Demsey, Diana Reiss, Marcelo O. Magnasco
bioRxiv (Cold Spring Harbor Laboratory) May 12, 2023 preprint DOI: 10.1101/2023.05.11.540348 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Case study Case report |
|---|---|
| Sample size | 1 |
| Population | One male Octopus insularis |
| Duration | One month of continuous video monitoring |
| Topics | Dreaming |
| Citations | 6 |
| Key findings | Four brief sleep-associated behavioral episodes (44-290 seconds) were observed in a single male Octopus insularis, during which it abruptly emerged from sleep and displayed antipredator and predatory behaviors with no predator present. The authors suggest the longest episode may have been a response to a negative episodic memory or a form of parasomnia, while noting that no rigorous conclusions can be drawn from one specimen. |
Abstract
ABSTRACT This paper presents some unusual behaviors observed in one single specimen of O. insularis . While nothing can be concluded rigorously from such data, we share the data and our analysis with the community, in the hope that others will be on the lookout for such rare events. Sleep is a fundamental biological function that is present in all tested vertebrates and most invertebrates. Cephalopods, such as octopuses, are cognitively complex animals that display active and inactive sleep states similar to those of vertebrates. In particular, octopuses have active sleep states during which they display sequences of camouflage patterns and modulation of basal rhythms, while remaining relatively unresponsive to outside stimuli. Some scientists have speculated that these states could be analogous to dreaming in mammals, involving episodic recall with a narrative structure. The convergent evolution of sleep in neurologically complex animals is a striking possibility, but its demonstration requires overcoming significant challenges. Towards this end, capturing abnormal sleep-associated episodes and other parasomnias in cephalopods can provide further insight into the biology of their sleep. This study reports abnormal behavioral episodes associated with transitions between activity states and sleep states observed in a male Octopus insularis . The study used continuous video monitoring to characterize the animal’s activity patterns and detect rare behavioral episodes. Over the course of a month, four brief episodes (duration range: 44-290 seconds) were identified during which the octopus abruptly emerged from quiescent or active sleep, detached itself from its sleep position, and engaged in antipredator and predatory behaviors (with no predator present). The longest of these episodes resembled the species-typical response to a predatory attack, suggesting that the animal may have been responding to a negative episodic memory or exhibiting a form of parasomnia. These findings, in conjunction with recent evidence for sleep in octopuses, highlight the complexity of possible sleep-associated behavioral episodes. Investigating sleep in invertebrates is crucial to understanding the evolution of sleep across distantly related species.
Comparable studies
Other case reports and case series on dreaming, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Lucid Dreaming as a Learnable Skill: A Case Study The author | 1980 | Case study | n = 1 |
| Lucid Dreaming as a Treatment for Recurrent Nightmares People with recurrent nightmares | 2010 | Case study | n = 5 |
| Treating Chronic Nightmares of Sexual Assault Survivors with an Intellectual Disability – Two Descriptive Case Studies Adults with learning disabilities suffering from post-traumatic nightmares | 2006 | Case study | n = 2 |
| Lucid dreaming: Correspondence between dreamed and actual events in one subject during rem sleep A lucid dreamer | 1984 | Case study | n = 1 |
| Lucid dreaming treatment for nightmares: A series of cases. Participants with nightmares | 2003 | Case series | n = 8 |