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Do split sleep/wake schedules reduce or increase sleepiness for continuous operations?

This study compared the impact of split and consolidated sleep/wake schedules on subjective sleepiness during the biological day and biological night. This was achieved using a between-group design involving two forced desynchrony protocols: consolidated sleep/wake and split sleep/wake. Both protocols included 7 × 28-h days with 9.33 h in bed and 18.67 h of wake each day. While the consolidated sleep/wake protocol had 1 × 9.33-h sleep opportunity and 1 × 18.67-h wake period each day, the split sleep/wake protocol had 2 × 4.67-h sleep opportunities and 2 × 9.33-h wake periods each day. For both protocols, subjective sleepiness was measured using the Karolinska Sleepiness Scale every 2.5 h during wake. A total of 29 healthy adult males participated, with 13 in the consolidated sleep/wake group (mean age = 22.5 yrs) and 16 in the split sleep/wake group (mean age = 22.6 yrs). On average, subjective sleepiness during wake periods of the split condition was significantly higher than that during the first half of wake periods of the consolidated condition, but was similar to the level during the second half. These findings were observed for wake periods that occurred during both the biological day and biological night. Previous data have shown that cognitive impairment at night is lower for split schedules than consolidated schedules, but the current data indicate that feelings of sleepiness are greater for split schedules than consolidated schedules for at least half of the time awake. Thus, it should be explained to people operating split sleep/wake schedules that although they may perform well, they are likely to feel sleepy.

Funding

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

History

Volume

99

Issue

B

Start Page

434

End Page

439

Number of Pages

6

eISSN

1879-2057

ISSN

0001-4575

Publisher

Elsevier

Language

en-aus

Peer Reviewed

Yes

Open Access

No

Acceptance Date

23/10/2015

External Author Affiliations

Appleton Institute for Behavioural Sciences; School of Human, Health and Social Sciences (2013- );

Era Eligible

Yes

Journal

Accident Analysis and Prevention