When early and late risers were left to their own devices: six distinct chronotypes under “lockdown” remained dissimilar on their sleep and health problems

ABSTRACT

Under national “lockdown,” the habitual late risers need not wake up early, and, similarly to the early risers, they don’t lose much sleep on weekdays. We tested whether, despite a decrease in weekday sleep loss, the difference between distinct chronotypes in health and sleep problems persisted during “lockdown.” Two online surveys were conducted from 10th to 20th of May, 2020 and 2021, one of them after 6 non-working weeks and another after 14 working weeks (during and after “lockdown,” respectively). Participants were students of the same grade at the same university department (572 and 773, respectively). The self-assessments included the Single-Item Chronotyping (SIC) designed for self-choosing chronotype among several their short descriptions and several questions about general health, mood state, outdoors and physical activity, and sleep concerns. The results suggested that the responses to each of the questions were not randomly distributed over 6 distinct chronotypes. Such a nonrandomness was identified within each of three pairs of these chronotypes, evening vs. morning types (with a rising throughout the day vs. a falling level of alertness, respectively), afternoon vs. napping types (with a peak vs. a dip of alertness in the afternoon, respectively), and vigilant vs. lethargic types (with the levels of alertness being permanently high vs. low, respectively). Morning, afternoon, and vigilant types reported healthier sleep/mood/behavior/habits than three other types. The most and the least healthy sleep/mood/behavior/habits were reported by morning and evening types, respectively. These relationships with health and sleep problems and the frequencies of 6 chronotypes remained unchanged after “lockdown.” Such results, in particular, suggested that the association of evening types with poorer health and sleep might not be attributed to a big amount of weekday sleep loss. The accounting for this association might help in designing interventions purposed on reduction of sleep and health problems.

KEYWORDS:

• Diurnal type
• alertness
• sleep-wake pattern
• sleep complaints
• mood
• Covid-19

Acknowledgements

The studies were supported by grants from the Russian Foundation for Basic Research (AAP by grant # 19-013-00424, and ROB and EVB by grant # 19-013-00568). ROB and EVB also obtained the support of their scientific projects from the North-Caucasus Federal University. We are indebted to Prof. Dr. Olivier Mairesse who pioneered the idea of development of one-click self-assessment of 4-6 chronotypes identified in our previous publication with his group (Putilov et al. 2019).

Disclosure statement

No potential conflict of interest was reported by the authors.

Ethical approval

The survey was conducted in accordance with the ethical standards of the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The Ethics Committee of the Medical Institute of the Peoples’ Friendship University of Russia approved the survey.

Authors contributions

AAP designed the survey, AAP and DSS designed the web page, AAP, DSS, ZBB, EBY, YPS, VIT, RPL, ROB, EVB, ANP, and VBD equally contributed to data collection and analysis, and AAP wrote the paper.

Data availability

The dataset is available on reasonable request to the corresponding author.