Chronic sleep restriction during development can lead to long-lasting behavioral effects

Abstract

Sleep abnormalities are highly correlated with neurodevelopmental disorders, and the severity of behavioral abnormalities correlates with the presence of sleep abnormalities. Given the importance of sleep in developmental plasticity, we sought to determine the effects of chronic sleep-restriction during development on subsequent adult behavior. We sleep-restricted developing wild-type mice from P5-P42 for 3h per day by means of gentle handling (n=30) and compared behavioral outputs to controls that were handled 10 min daily (n=33). We assayed activity in the open field, social behavior, repetitive behavior, and anxiety immediately following sleep restriction and after four weeks of recovery. At six weeks of age, immediately following chronic sleep-restriction, mice were less active in an open field arena. Sociability was increased, but repetitive behaviors were unchanged in both males and females. After a 4-week period of recovery, some behavioral abnormalities persisted and some became apparent. Sleep-restricted mice had decreased activity in the beginning of an open field test. Female mice continued to have increased sociability and, in addition, increased preference for social novelty. In contrast, male mice demonstrated decreased sociability with medium effect sizes. Repetitive behavior was decreased in sleep-restricted female mice and increased in males. Measures of anxiety were not affected in the sleep-restricted mice. These results indicate that chronic sleep restriction during development can lead to long-lasting behavioral changes that are modulated by sex. Our study may have implications for a role of disrupted sleep in childhood on the unfolding of neurodevelopmental disorders.

Keywords: Gentle handling; Open field activity; Repetitive behavior; Sleep restriction; Social behavior.

Figure 1

Decreased activity in the open-field arena following chronic sleep-restriction. (A) Horizontal distance traveled in the open-field (cm) is plotted by epoch (five min each) for a 30 minute test period for animals two days following completion of chronic sleep restriction. Main effects of condition and epoch were statistically significant indicating that sleep-restricted mice had reduced exploratory activity compared to controls and that all groups had higher levels of activity at first followed by evidence of habituation. (B) Distance traveled in the open field following four weeks recovery sleep. The Condition × Epoch and Sex × Epoch interactions were statistically significant, indicating that sleep-restricted mice reacted less to the novel environment than controls and that females reacted more to the novel environment than males. All mice showed some tendency to habituate to the novel conditions over the 30 min test (main effect of epoch). (C) The ratio of distance traveled in the center to total distance traveled two days following completion of chronic sleep restriction. The main effect of epoch, was the only statistically significant effect. (D) The ratio of distance traveled in the center to total distance traveled after four weeks of recovery sleep. The main effect of epoch was the only statistically significant effect, and the Condition × Epoch interaction approached statistical significance (p=0.055). Data plotted are the means ± SEMs for (A&C) 10 control male, 11 sleep-restricted male, 17 control female, and 15 sleep-restricted female mice, and for (B&D) 11 control male, 11 sleep-restricted male, 22 control female, and 16 sleep-restricted female mice. Error bars are largely within the confines of the symbol.

Figure 2

Behavior in the elevated plus maze four weeks post-recovery. Anxiety-like behavior as indicated by time in the open arms of the maze was not affected by chronic developmental sleep-restriction. Bars represent the means ± SEMs for 11 control male, 13 sleep-restricted male, 22 control female, and 17 sleep-restricted female mice.

Figure 3

Results of rotarod testing four weeks post recovery showed normal motor function. Bars represent means ± SEMs for 11 control male, 13 sleep-restricted male, 21 control female, and 17 sleep-restricted female mice. Each mouse was tested twice for latency to fall off a rotarod accelerating at 0.1 rpm/second.

Figure 4

Social behavior is altered in mice one day following chronic sleep restriction. (A) Sociability test: time spent in the chamber measured at one day following completion of chronic sleep-restriction (pre-recovery) shows a statistically significant Condition × Chamber interaction and a simple effect of chamber. Sleep-restricted mice regardless of sex spent more time in the chamber with the stranger mouse than did control mice. (B) Sociability test: sniffing time measured one day following chronic sleep-restriction (pre-recovery) reveals a statistically significant Condition × Chamber interaction. Main effects of condition and chamber were also statistically significant. Sleep-restricted mice had increased sociability compared to control mice one day following chronic sleep-restriction (pre-recovery). (C) Social novelty test: time spent in the chamber one day following chronic sleep restriction (pre-recovery) shows a statistically significant main effect of chamber that does not change depending on condition. (D) Social novelty test: sniffing time measured one day following chronic sleep-restriction (pre-recovery) reveals a statistically significant main effect of chamber and a near statistically significant main effect of sex, but no statistically significant effect of condition. Bars represent the means ± SEMs in (A&C) 11 control male, 13 sleep-restricted male, 22 control female, and 17 sleep-restricted female mice, and in (B&D) 10 control male, 13 sleep-restricted male, 21 control female, and 17 sleep-restricted female mice.

Figure 5

Social behavior is altered even after four weeks of recovery from chronic sleep-restriction. (A) Sociability test: time spent in the chamber after four weeks of recovery sleep (post-recovery) shows a statistically significant Sex × Chamber interaction and a near significant Sex × Condition interaction, indicating a sex-specific differential response to sociability post-recovery. Main effects of condition and chamber were statistically significant. (B) Sociability test: time spent sniffing following four weeks of recovery sleep (post-recovery) reveals a statistically significant Sex × Chamber interaction. Main effects of condition and chamber were also statistically significant. There was a close to statistically significant Condition × Sex × Chamber interaction. A post-hoc pairwise analysis reveals that sleep-restricted male mice had a trend toward statistically significant increase in time spent sniffing the object compared to controls. Sleep-restricted female mice had a statistically significant increase in time spent sniffing the stranger and a near significant increase in time spent sniffing the object compared to controls. These data show abnormalities in sociability following chronic sleep restricted that is sex dependent. (C) Social novelty test: time spent in the chamber following four weeks of recovery sleep (post-recovery) shows a statistically significant Sex × Chamber interaction and a statistically significant main effect of chamber. (D) Social novelty test: time spent sniffing measured four weeks after recovery sleep (post-recovery) reveals a statistically significant main effect of chamber, and a statistically significant Sex × Chamber, Sex × Condition, and Sex × Condition × Chamber interaction. A post-hoc pairwise analysis shows that sleep-restricted female mice had a statistically significant increase in time spent sniffing the novel mouse compared to controls. Bars represent the means ± SEMs in 11 control male, 13 sleep-restricted male, 22 control female, and 17 sleep-restricted female mice.

Figure 6

Marble burying differences are differentially regulated by sex following chronic sleep restriction. (A) No statistically significant differences were found in marble burying behavior three days following chronic sleep-restriction (pre-recovery). (B) After four weeks of recovery sleep (post-recovery), there was a statistically significant Sex × Condition interaction. A post-hoc pairwise analysis showed that female sleep-restricted mice buried significantly fewer marbles than control mice. These data show sex-specific changes in repetitive behaviors following chronic sleep restriction. Bars represent the means ± SEMs in (A) 9 control male, 13 sleep-restricted male, 19 control female, and 17 sleep-restricted female mice, and in (B) 11 control male, 13 sleep-restricted male, 22 control female, and 17 sleep-restricted female mice.

Figure 7

Sleep behavior following chronic sleep restriction. Averaged percent time asleep, after 11 weeks of recovery sleep (17 weeks of age), showed a statistically significant main effect of sex and phase, and a significant interaction between Sex × Phase. There was a trend toward an effect of condition (p=0.093), in which sleep-restricted mice showed increased time sleeping compared to control mice. Bars represent the means ± SEMs in 9 control male, 11 sleep-restricted male, 14 control female, and 11 sleep-restricted female mice.