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The endogenous circadian temperature period length (tau) in delayed sleep phase disorder compared to good sleepers

journal contribution
posted on 06.12.2017, 00:00 by G Micic, A de Bruyn, N Lovato, H Wright, M Gradisar, Sally FergusonSally Ferguson, H Burgess, L Lack
The currently assumed aetiology for delayed sleep phase disorder (DSPD) is a delay of the circadian system. Clinicians have sought to use bright light therapy, exogenous melatonin or chronotherapy to correct the disorder. However, these treatments have achieved unreliable outcomes for DSPD patients and, as such, one sugggestion has been that the disorder may be caused by a longer than normal circadian rhythm period length (i.e. tau). The present study investigated this premise using a 78-h ultradian, ultra-short sleep-wake cycle. This constant bedrest routine was used to simulate a series of 1-h long 'days' by alternating 20-min sleep opportunities and 40 min of enforced wakefulness. Thirteen participants were recruited for the study including, six people diagnosed with DSPD according to the International Classification of Sleep Disorders - 2 [mean age = 22.0, standard deviation (SD) = 3.3] and seven good sleepers (mean age = 23.1, SD = 3.9) with normal sleep timing. The DSPD participants' core temperature rhythm tau (mean - 24 h 54 min, SD = 23 min) was significantly longer (t = -2.33, P = 0.04, Cohen's d = 1.91) than the good sleepers' (mean 24 h 29 min, SD = 16 min). The temperature rhythm of the DSPD participants delayed more rapidly (i.e. >25 min day-1) than the good sleepers'. These findings provide an explanation for the difficulty that DSPD patients have in phase advancing to a more conventional sleep time and their frequent relapse following treatment. The outcomes of this study support a vigorous and continued application of chronobiological and behavioural therapies to entrain DSPD patients to their desired earlier sleep times.

Funding

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

History

Volume

22

Issue

6

Start Page

17

End Page

24

Number of Pages

8

eISSN

1365-2869

ISSN

0962-1105

Location

United Kingdom

Publisher

Wiley Blackwell

Language

en-aus

Peer Reviewed

Yes

Open Access

No

External Author Affiliations

Appleton Institute for Behavioural Sciences; Flinders University; Not affiliated to a Research Institute; Rush University Medical Center;

Era Eligible

Yes

Journal

Journal of sleep research.