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Data analysis and research: Nicky Forster
Design and illustration: Peter Hamlin, Philip Holm
Web development and visualization: Hyojin Yoo, Caleb Diehl, Parker Kaufmann
Story concept and reporting: Christina Larson
Editors: Mary Sedor, Alicia Chang
Creative direction: Darrell Allen, Linda Gorman
Audience coordination and production: Kyle Viterbo, Nelly Ontiveros Cervantes
Chinstrap Penguin microsleep data:
P.-A. Libourel, W. Y. Lee, I. Achin, H. Chung, J. Kim,
B. Massot, N. C. Rattenborg, Nesting chinstrap penguins
accrue large quantities of sleep through seconds-long
microsleeps, Science (2023). Researchers provided data to AP upon request.
https://www.science.org/doi/10.1126/science.adh0771
Frigatebird sleep flight data:
N. Rattenborg, B. Voirin, S. Cruz, R. Tisdale, G.
Dell’Omo, H.-P. Lipp, M. Wikelski, A. Vyssotski.
Evidence that birds sleep in mid-flight. Nat Commun *7*,
12468 (2016). Researchers provided data to AP upon request.
https://doi.org/10.1038/ncomms12468
Elephant seal sleep dive data:
J. M. Kendall-Bar, T. M. Williams, R. Mukherji, D. A.
Lozano, J. K. Pitman, R. R. Holser, T. Keates, R. S.
Beltran, P. W. Robinson, D. E. Crocker, T. Adachi, O. I.
Lyamin, A. L. Vyssotski, D. P. Costa, Brain activity of
diving seals reveals short sleep cycles at depth, Dryad
(2023). https://doi.org/10.7291/D1ZT2B (Accessed 9-3-2025)