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Dynamics of neurobehavioral performance variability under forced desynchrony : evidence of state instability

journal contribution
posted on 06.12.2017, 00:00 by Xuan Zhou, D Kennaway, David Darwent, Gregory Roach, Raymond Matthews, Sally Ferguson, Charli Sargent
Study Objectives: The state instability hypothesis posits that increasing sleep drive brings about escalating state instability in attention, making neurobehavioral performance increasingly variable. This hypothesis predicts that performance variability is a function of prior wake, circadian phase, and time on task. These predictions have been supported when wakefulness is beyond the habitual wake period. Our study aimed to test these predictions within the habitual wake period. Design: A 12-calendar-day 28-h forced desynchrony protocol consisting of 7 repetitions of a 28-h sleep/wake cycle, with two-thirds time awake and one-third time in bed. Each wake period included 7 equally spaced 1-h testing sessions. Setting: A time-isolation sleep laboratory. Participants: Thirteen young healthy males. Interventions: Wake periods during the protocol were 4 h delayed each 28-h “day” relative to the circadian system, such that they were distributed across the whole circadian cycle. This allowed performance testing at different combinations of prior wake of a habitual length (i.e., < 18 h) and circadian phase. Measurements and Results: Performance variability was indexed by standard deviation of response times within a 10-min psychomotor vigilance task. We found that response times became more variable with increasing wakefulness and towards circadian nadir, i.e., when sleep drive was increasing. These changes in response time variability were however not dependent on time on task, which is likely due to the modest level of sleep drive in our study. Conclusions: The state instability hypothesis, as an explanation for the responsiveness of neurobehavioral performance to increasing sleep drive, is supported during the habitual wake period.

Funding

Category 1 - Australian Competitive Grants (this includes ARC, NHMRC)

History

Volume

34

Issue

1

Start Page

57

End Page

63

Number of Pages

7

ISSN

0161-8105

Location

United States

Publisher

Associated Professional Sleep Societies, Llc

Language

en-aus

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

Centre for Sleep Research; University of Adelaide;

Era Eligible

Yes

Journal

Sleep.