The Song of Sleep

Crane Fly and Ants
Joris Hoefnagel, illuminator (Flemish / Hungarian, 1542 – 1600)
Georg Bocskay, scribe (Hungarian, died 1575)


By Jason G Goldman

“Almost all other animals are clearly observed to partake in sleep, whether they are aquatic, aerial, or terrestrial,” wrote Aristotle in his work, On Sleep and Sleeplessness.
In The History of Animals, he wrote: “It would appear that not only do men dream, but horses also, and dogs, and oxen; aye, and sheep, and goats, and all viviparous quadrupeds; and dogs show their dreaming by barking in their sleep.”

Researchers can now humanely peer into the electrical and chemical activities of brain cells in animals while they sleep. In 2007, MIT scientists Kenway Louise and Matthew Wilson recorded the activity of neurons in a part of the rat brain called the hippocampus, a structure known to be involved in the formation and encoding of memories. They first recorded the activity of those brain cells while the rats ran in their mazes.
Then they looked at the activity of the very same neurons while they slept and discovered identical patterns of firing during running and during REM.
In other words, it was as if the rats were running the maze in their minds as they slept. The results were so clear that the researchers could infer the rats’ precise location within their mental dream mazes and map them to actual spots within the actual maze.

University of Chicago biologists Amish Dave and Daniel Margoliash looked into the brains of zebra finches and discovered something similar.
These birds are not born with the melodies of their songs hardwired into the brains; instead, they have to learn to sing their songs. When they’re awake, the neurons in part of the finches’ forebrain called the robutus archistriatalis fire following their singing of particular notes. Researchers can determine which note was sung based on the firing patterns of those neurons. By piecing together the electrical patterns in those neurons over time, Dave and Margoliash can reconstruct the entire song from start to finish.

Later, when the birds were asleep, Dave and Margoliash looked again at the electrical activity in that part of their brains. The firing of those neurons wasn’t entirely random. Instead, the neurons fired in order, as if the bird was audibly singing the song, note for note. It might be said that the zebra finches were practising their songs in their sleep.


Ants are good sleep research subjects, as they live underground. Most ants get exposed to sunlight only very irregularly, so a sleeping rythm based on a photo period like ours would not be very useful. Because of their social and subterranean lifestyle, one might expect that sleep periods of ants are more dependent on the tasks at hand than on light/dark periods.

This is indeed what Deby Cassill and collaborators found. Queens of the fire ant (Solenopsis invicta) have an average of 92 sleep periods per day, lasting for about 6 minutes each (for a total of 9.4h of sleep per day). Workers are very different from this, as they had 253 sleep episodes on average per day, each lasting about 1 minute, for a total of 4.8h sleep per day, meaning they sleep more often, but less long. At any time of the day, about 80% of the work force was actually working instead of sleeping, which is an efficient pattern.

REM (Rapid Eye Movement) sleep is the phase where we ‘blink’ our eyes often, and it’s the phase where our dreams are the most vivid; the dreams we actually remember occur during this sleep phase.
Ant queens show a similar behaviour when they’re fast asleep. Instead of their eyes, they twitch their antennae, resulting in so called ‘Rapid Antennal Movement’ (RAM) sleep.


Cassill DL, Brown S, Swick D, Yanev G (2009) Polyphasic wake/sleep episodes in the fire ant Solenopsis invicta. Journal of Insect Behaviour 22:313-323



On the Nature of Things

hoefnagel sloth

 Now come, and next hereafter apprehend
What sorts, how vastly different in form,
How varied in multitudinous shapes they are-
These old beginnings of the universe;
Not in the sense that only few are furnished
With one like form, but rather not at all
In general have they likeness each with each,
No marvel: since the stock of them’s so great
That there’s no end (as I have taught) nor sum,
They must indeed not one and all be marked
By equal outline and by shape the same.
Moreover, humankind, and the mute flocks
Of scaly creatures swimming in the streams,
And joyous herds around, and all the wild,
And all the breeds of birds- both those that teem
In gladsome regions of the water-haunts,
About the river-banks and springs and pools,
And those that throng, flitting from tree to tree,
Through trackless woods- Go, take which one thou  wilt,
In any kind: thou wilt discover still
Each from the other still unlike in shape.

De rerum natura
c. 50 B.C.E

Translated by William Ellery Leonard

Beneath a canopied structure, a wiry-haired animal, perhaps a sloth, munches on a twig. A Latin text based on Jesus’s Sermon on the Mount appears above. Although the text and image seem to fit perfectly together, the different elements on the page were made thirty years apart.The elegant Roman-style lettering was written by Georg Bocskay to display his mastery of calligraphy. The text originally appeared on a plain black background. The illustration was added later by Joris Hoefnagel, who saw in the diminishing script the suggestion of recession into space, an illusion defied by the two-dimensionality of the text. He thus enclosed the letters within an architectural canopy drawn in perspective. Hoefnagel also responded wittily to the black coloration of the page, interpreting it naturalistically as nighttime: the silvery tones of the animal’s fur and the gold shimmer in the darkness.

Joris Hoefnagel illuminator, Georg Bocskay, scribe
Flemish and Hungarian illumination 1591-1596, script 1561-1562
Watercolors, gold and silver paint, and ink on parchment