English translation of the first study reporting cyclical periods of increased respiration and eye and body motility during sleep in infants in 1926, with commentary

Abstract

This is the first English translation of the work Periodic phenomena in the sleep in children, published in 1926 in the Journal Novoe v refleksologii i fiziologii nervnoi sistemy (Vol. 2, pp. 338-345) by Maria Denisova and Nicholai Figurin; it is the first study to report data on what is currently termed rapid eye movement (REM) sleep. The authors acquired continuous quantitative respiration data, as well as, eye and body movements during sleep in children for up to 6 hours, and discovered several novel features of sleep cycles in healthy infants from birth to about 1 year of age. First, the study reports cyclical periods of increased respiration and eye and body movements, with rapid ocular movements visible under relaxed eyelids (separation: 0.5-1 mm). These observations suggest atonia of REM sleep. Second, the length of the complete cycle (alternating active and quiet sleep phases or states) is about 50 minutes, an estimate that is consistent with later work. Third, the study identifies infant-specific ordering of sleep states, with the active phase beginning after sleep onset, followed by the quiescence phase. Importantly, these published data on sleep cycles precede all published studies related to the state now termed REM sleep by about 30 years (i.e. publishing in Science and in the Journal of Applied Physiology in the 1950s by Eugene Aserinski and Nathaniel Kleitman). In the historical commentary accompanying this translation, the findings of those later works are carefully compared to the original data on respiration and ocular and body motility cycles during sleep in infants, first reported and published by Denisova and Figurin (1926).

Keywords: movements in infants; rapid eye movements; sleep in infants; stages of sleep in infants.

Graphical Abstract

Figure 1.

Respiration and eye and body motility cycles during sleep in infants were first reported in 1926 by M. Denisova and N. Figurin. The top of the schematic overviews the methods and devices used in the study, while the bottom presents overall findings of distinct, alternating phases during sleep, currently termed active sleep (or rapid eye movement, REM) and quiet sleep (NREM). (This summary illustration is made by K. Denisova for this commentary.)

Figure 2.

Curve No.1 (Name: Zoya B. [girl]; Age: 1 month 15 days). Explanation for curve No. 1: the values from 20 to 50 on the vertical axis indicate the number of breaths per minute. The values at the top indicate minutes from sleep onset. Points (^.) = general movements. Dashes (::) = movements of eyelids and eyes. M = urination. Figure is from [Denisova, M. P. and Figurin, N. L. (1926). Periodic phenomena in the sleep of children. Novoe v refleksologii i fiziologii nervnoi sistemy, 2, 338–345]. This material is provided solely for scientific and educational uses.

Figure 3.

Curve No.2 (Name: Kolya H. [boy]; Age: 2 months). Curve No.3 (Name: Slavik F. [boy]; Age: 8 months 9 days). Curve No.4 (Name: Leyla M. [girl]; Age: 1 year 19 days). Figure is from [Denisova, M. P. and Figurin, N. L. (1926). Periodic phenomena in the sleep of children. Novoe v refleksologii i fiziologii nervnoi sistemy, 2, 338–345]. This material is provided solely for scientific and educational uses.

Figure 4.

Curve No.5 (Name: Zoya B. (girl); Age: 4 months 2 days). Figure is from [Denisova, M. P. and Figurin, N. L. (1926). Periodic phenomena in the sleep of children. Novoe v refleksologii i fiziologii nervnoi sistemy, 2, 338–345]. This material is provided solely for scientific and educational uses.

Figure 5.

Curve No.6 (Name: Zhenya; Age: 4 months). Pneumographic curve at the onset of period with increased rapidity of breathing. Figure is from [Denisova, M. P. and Figurin, N. L. (1926). Periodic phenomena in the sleep of children. Novoe v refleksologii i fiziologii nervnoi sistemy, 2, 338–345]. This material is provided solely for scientific and educational uses.

Figure 6.

Curve No.7 (Name: Leva S. [boy]; Age: 4 years). Figure is from [Denisova, M. P. and Figurin, N. L. (1926). Periodic phenomena in the sleep of children. Novoe v refleksologii i fiziologii nervnoi sistemy, 2, 338-345]. This material is provided solely for scientific and educational uses.

Figure 7.

Curve No.8 (Name: Vera I. [girl]; Age: 5 months 20 days). Curve No.9 (shows data from the same child, a few days later) (Name: Vera I.; Age: 5 months 23 days). Explanation for curve No.9: symbol “^” marks the minutes (shown at ~28, 88, 160, and 198 minutes) when the child was turned over to the other side. Figure is from [Denisova, M. P. and Figurin, N. L. (1926). Periodic phenomena in the sleep of children. Novoe v refleksologii i fiziologii nervnoi sistemy, 2, 338–345]. This material is provided solely for scientific and educational uses.