Neurobehavioral functions during recurrent periods of sleep restriction: effects of intra-individual variability in sleep duration

Longitudinal assessment of objective sleep and power output in Division I collegiate baseball athletes

OBJECTIVES

Many college athletes experience insufficient sleep due to athletic, academic, and social constraints. While prior studies have observed cross-sectional associations between poor sleep and performance in athletes, few studies have longitudinally assessed performance variations in relation to sleep measures. We investigated whether objectively measured sleep assessments were associated with peak power output improvements during a fall season of Division I collegiate baseball players.

METHODS

Peak power output was assessed weekly for 12weeks in 24 male collegiate baseball players (age: 21±1years). Objective sleep (Oura ring) was assessed over the final 6weeks to determine total sleep time, sleep efficiency, and other assessments of sleep quality, including the proportion of nights in which athletes maintained total sleep time ≥7 hours or sleep efficiency ≥90%. Bivariate correlations between sleep measures and peak power output were performed.

RESULTS

Greater improvements in peak power output throughout the fall season were associated with higher total sleep time (r=0.429, p=.036), higher sleep efficiency (r=0.411, p=.046), and fewer nighttime awakenings (r=-0.495, p=.014). Furthermore, the rate of change in peak power output was associated with the proportion of nights in which athletes maintained total sleep time ≥7 hours (r=0.557, p=.005) or sleep efficiency ≥90% (r=0.509, p=.011).

CONCLUSIONS

These findings support an association between adequate sleep duration, quality, and consistency in training season performance trajectories in college athletes.

DATA AVAILABILITY

Data will be made available upon reasonable request by the corresponding author.

Objective and Subjective Intraindividual Variability in Sleep: Predisposing Factors and Health Consequences

OBJECTIVE

We investigated the factors that predispose or precipitate greater intraindividual variability (IIV) in sleep. We further examined the potential consequences of IIV on overall sleep quality and health outcomes, including whether these relationships were found in both self-reported and actigraphy-measured sleep IIV.

METHODS

In Study 1, 699 US adults completed a Sleep Intra-Individual Variability Questionnaire and self-reported psychosocial, sleep quality, and health outcomes. In Study 2, 100 university students wore actigraphy and completed psychosocial, sleep, and health surveys at multiple timepoints.

RESULTS

In cross-sectional analyses that controlled for mean sleep duration, predisposing/precipitating factors to greater IIV were being an underrepresented racial/ethnic minority (Study 1: F = 13.95, p < .001; Study 2: F = 7.03, p = .009), having greater stress (Study 2: r values ≥ 0.32, p values ≤ .002) or trait vulnerability to stress (Study 1: r values ≥ 0.15, p values < .001), and showing poorer time management (Study 1: r values ≤ -0.12, p values ≤ .004; Study 2: r values ≤ -0.23, p values ≤ .028). In addition, both studies showed that greater sleep IIV was associated with decreased overall sleep quality, independent of mean sleep duration (Study 1: r values ≥ 0.20, p values < .001; Study 2: r values ≥ 0.33, p values ≤ .001). Concordance across subjective and objective IIV measures was modest ( r values = 0.09-0.35) and similar to concordance observed for subjective-objective mean sleep duration measures.

CONCLUSION

Risk for irregular sleep patterns is increased in specific demographic groups and may be precipitated by, or contribute to, higher stress and time management inefficiencies. Irregular sleep may lead to poor sleep quality and adverse health outcomes, independent of mean sleep duration, underscoring the importance of addressing sleep consistency.