Circadian variation in cognition: a comparative study between sleep-disturbed and healthy participants

ABSTRACT

Aims: To understand the circadian variation in cognition over the course of the day in sleep-disturbed (SD) participants and to compare the findings with healthy controls.

Methods: Subjects were screened using Pittsburgh sleep quality index (PSQI), and a total of 24 participants (12 SD and 12 controls) were recruited for the study. P300 was recorded five times a day (8 a.m., 11 a.m., 2 p.m., 5 p.m. and 8 p.m.) for all the participants in both the groups.

Results: The results revealed significant variations in P300 wave in both the groups at different time points. The P300 amplitude at 5 p.m. was significantly higher than that at 8 a.m. and 11 a.m., and the lowest peak was recorded at 8 p.m. preceded by that at 2 p.m. for healthy participants. In SD subjects, the highest amplitude was recorded at 8 p.m., followed by 5 p.m., whereas the lowest deflection was recorded at 2 p.m. preceded by 11 a.m. and 8 a.m. Similarly, P300 latency showed the longest value at 8 a.m. followed by 2 p.m., and further followed by 8 p.m. Shortest latency was recorded at 5 p.m. in non-SD participants, whereas SD participants demonstrated a contrasting trend with the longest latency being recorded at 2 p.m., followed by 8 a.m. and 5 p.m. Shortest latency was observed at 8 p.m. preceded by 11 a.m.

Conclusion: These results suggest that P300 characteristics vary along the span of the day between SD and non-SD participants.

Clinical trial registry: CTRI/2019/05/019154

KEYWORDS:

• Cognitive function
• P300
• Event-related-potential
• Time-of–day

Acknowledgments

Authors would like to thank Mohd. Salman, Medical Electrophysiology Technician, Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia for providing us with technical help with the equipment.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Department of Science and Technology (DST), Government of India, under Cognitive Science Research Initiative (CSRI), Sanction No. DST/CSRI/2017/209.