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Chronobiology International
The Journal of Biological and Medical Rhythm Research
Volume 40, 2023 - Issue 4
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Research Article

Morning affect or sleep inertia? Comparing the constructs and their measurement

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Pages 458-472 | Received 19 Dec 2022, Accepted 28 Feb 2023, Published online: 13 Mar 2023
 

ABSTRACT

The construct of Morning Affect (MA; alertness upon awakening/time required to feel fully awake) emerged from exploratory factor analysis of morningness-eveningness questionnaires, and while it has been equated with morningness-eveningness preference it has much conceptual overlap with sleep inertia (SI; the transitional state between sleep and being fully awake). The current study compared questionnaire measures of these constructs to help clarify their inter-relationships. A volunteer sample of 453 students at an English-medium university in China completed an online survey including the Sleep Inertia Questionnaire (SIQ), the Morningness-Eveningness-Stability-Scale-improved (MESSi), with subscales for MA, Eveningness, and Distinctness (amplitude of diurnal variation), and the reduced Morningness-Eveningness Questionnaire (rMEQ). Measures of depression, sleep quality, mindfulness, and personality were also included. Exploratory factor analysis of the SIQ, MESSi, and rMEQ items revealed seven factors: Cognitive, Emotional, and Physiological SI, Responses to SI (including one MA item), and Duration of SI (one SIQ item, 3/5 MA items, and one rMEQ item); Morningness-Eveningness (MESSi Eveningness items, plus 3/5 rMEQ items); Distinctness (3/5 MESSi items). These results suggest that Morning Affect may be better characterised as a general measure of sleep inertia, and may contribute to ongoing development/refinement of questionnaire measures of circadian functioning.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/07420528.2023.2187211.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.