Primate Sleep Discussion

The following is a transcript from the original Primate Info Net of a discussion about primate sleep that took place on the Primate-Talk email list in October 1997. A brief general bibliography follows.


Date: Wed, 08 Oct 1997 10:58:12 +0100
From: Robin Walker <>
Subject: R.E.M sleep and Nesting

A client who is a consultant neurologist asked me today about R.E.M. (rapid eye movement) sleep in dogs and humans. She observed that whereas in Man during R.E.M. as state of “sleep paralysis” generally prevails in the dogs it seems that the body can exhibit a great deal of motion. Her question was why should two mammals exhibit such an apparently opposite condition?

As I only had the time it took to accept her cheque and show her to the door with her cat, my answer was rather short and unresearched. I said that I thought ;that sleep paralysis might be highly adaptive in creatures which nest in trees (being mindful of movies of gorillas nest making in treetops) and therefore would be in danger if dreaming* was accompanied by activity.

Is there any work on R.E.M sleep in arboreal primates? Might baboons be different? Could we have a evolved trait from an early arboreal nesting habit?

Robin Walker.


From: Evan Zucker (
Wed, 8 Oct 1997 11:50:50 -0500 (CDT)

The “paralysis” associated with REM sleep does not mean that muscles cannot be moved – it means that the movements are not under the (voluntary) control of the sleeper. My understanding is that all mammals and birds show REM sleep to some extent.

Humans twitch and move during REM sleep, but there is no control of these movements. The sleep disorder called REM sleep behavior disorder (or REM without atonia) is where the paralysis does not occur, and people/primates/mammals do move – and are capable of acting out their dreams.

Evan L. Zucker
Dept. of Psychology
Loyola University
New Orleans, LA 70118 USA


From: Cobie Brinkman (
Thu, 9 Oct 1997 11:32:02 +1100

Dear Pters: Before going on about REM sleep, while it is true that there is a kind of paralysis caused by lack of excitatory drive to the nerve cells controlling the muscles, this paralysis is fairly frequently interrupted by brief bursts of ‘breakthrough’ activation, so muscle twitching is observed. Observing a dog lying totally relaxed on its side, you may see movements of the paws, and twitching of the face (and of the eyes which gives the phenomenon its name Rapid Eye Movement sleep). Possibly correctly, we say: he must be dreaming about chasing something.. humans dream in REM sleep (at least, when woken up from it, we remember our dreams – we also dream in other sleep phases but do not remember dreams as clearly).

The general answer is that all mammals appear to need REM sleep but that how you get it relates to your life style (dolphins sleep one hemisphere of the brain at the time, herbivores would not like to be paralysed lying down for long periods – this can be seen even in our domestic animals: horses lie down “flat” very rarely, although they may lie down “head up” in sternal recumbancy in a drowsy state most of the night) and your age (human and other mammalian babies have a much longer REM sleep period than adults). There may be more recent data (there are on sleep in general) but according to a Table in “The Sleeping Brain” (MH Chase, ed; Brain Information Service, University of California, Los Angeles), p. 35, Galago senegalensis spends 11.2% of its sleep time in REM; Vervet monkeys (subadult), 5.6%; Patas (subadult), 7.9%; laboratory baboons, 7.3%; wild baboons, 5.9%; 3 subadult Macaca species, 11.5% (radiata), 11.1% (nemestrina); and 15.5% (mulatta); chimps, 15%. All other species mentioned were adult animals. For the record, Homo sapiens in utero: 80% (as seen in 10 wks premature babies);6 wks pre, 60%; normal neonate, 50%; 10-60 years, 25%; 80 yrs, 20%.

Interestingly, it is in the nonREM sleep stages that the primate species differ most, according to this Table. So are chimps paralysed in thier nests? Probably, at least some of the time. However, they really have little to worry about re predators, so they can afford to dream 🙂 and given that they are social, there probably will be some animals around that are just dozing and are easily aroused to wake up the rest if needed?

Cheers all, Cobie

Dr Cobie Brinkman
Australian National University
Division of Psychology
Canberra Australia 0200
Tel. +61-6-2492803 Fax +61-6-2490499
e-mail <;

——————————————————————————- (Joe Erwin)
Thu, 9 Oct 1997 10:01:00 -0400 (EDT)

Dear Cobie,
I just want to express how much I enjoyed reading your exemplary essay/message regarding primate sleep and dreaming. What an outstanding example that is of the best of PT communication.

Further, this presentation of information shows how important it is to bridge the gap between natural history, field studies, and lab studies (all carefully and humanely conducted, of course), of human and all other nonhuman primates (and other animals) of all ages.

Best wishes, Cobie, and thanks!


General Bibliography on Primate Sleep and REM

Anderson, JR. “Sleeping sites and sleep-related activities: Awakening to their significance.” IPS/ASP CONGRESS ABSTRACTS (1996): #745, 1996.

Fruth, B. “Social and ecological aspects of nest-building behavior in wild pygmy chimpanzees (Pan paniscus).” PRIMATE REPORT (31): 13-14, 1991.

Fruth, B. and WC McGrew. “Resting and nesting in primates: behavioral ecology of inactivity.” IPS/ASP CONGRESS ABSTRACTS (1996): #743, 1996.

Henn, V., D. Straumann and Y. Suzuki. “Generation of rapid eye movements in 3 dimensions.” BIOMEDICAL RESEARCH 14 (Suppl. 1): 67-69, 1993.

Henn, V. and K. Hepp. “Pathophysiology of rapid eye movement generation in the primate.” PROGRESS IN BRAIN RESEARCH 64: 303-312, 1986.

Henn, V., K. Hepp and T. Vilis. “Rapid eye movement generation in the primate. Physiology, patho-physiology, and clinical implications.” REVUE NEUROLOGIQUE 145(8-9): 540-545, 1989.

Vilis, T., K. Hepp, U. Schwartz, and v. Henn. “On the generation of vertical and torsional rapid eye movements in the monkey.” EXPERIMENTAL BRAIN RESEARCH 77(1): 1-11, 1989.

Zhou, W. and WM King. “Binocular coordination of eye movements during wakefulness, non-REM and REM sleep in monkeys. SOCIETY FOR NEUROSCIENCE ABSTRACTS 21 (Pt. 2): 922, 1995.