The effect of 24-hour sleep deprivation on subjective time perception

Body temperature and time perception in morning and evening types

Previous studies have suggested that time perception fluctuates throughout the day in relation to daily fluctuations of body temperature, and that there is a negative relationship between body temperature and time perception. The aim of this study was to examine, using behavioral and physiological methods, whether evening and morning types differ in their time perception at different times of day using different stimulus durations and whether there is a negative relationship between time perception, body temperature and social jet lag. This study was conducted with 33 participants (17 morning types and 16 evening types) who performed a time production task in four experimental sessions, set on two consecutive days at two times of the day (08.30-10.00 h, 15.30-17.00 h) with four stimulus durations (1, 5, 10 and 15 s). The Morningness-Eveningness Questionnaire (MEQ) and the Munich Chronotype Questionnaire-Turkish version (MCTQ-TR) were used to determine chronotype and social jet lag respectively. The results showed that the produced time was shorter in the evening session than in the morning session. Four stimulus durations were underestimated, and the underestimation increased with stimulus duration. There was also a significant increase in body temperature from morning to evening, but there was no relationship between time perception and body temperature. These results did not support the hypothesis that there is a relationship between time perception and body temperature.

Relationship Between Sleep Time and Depressive Symptoms in Middle-Aged and Elderly Chinese: Mediating Role of Body Pain

Objective

Existing research has yet to adequately examine the correlation between sleep time, body pain, and depressive symptoms. This study seeks to elucidate the interconnections between these three elements.

Methods

The study used 2020 CHARLS data for analysis. To assess the intricate association among sleep time, body pain, and depressive symptoms, the study employed Spearman correlation analysis, multiple logistic regression, restricted cubic splines, and mediation effect analysis based on bootstrap testing.

Results

Risk factors for depressive symptoms in middle-aged and elderly Chinese include physical pain and reduced sleep duration. Results from the RCS suggest that the lowest risk of depressive symptoms occurs when the sleep time for the middle-aged and elderly population is approximately 7.5 hours. Body pain accounts for a 19.05% mediating effect between sleep time and depressive symptoms, and even after controlling confounding factors, there remains a 7.5% mediating effect.

Conclusion

The research findings indicate that there is a significant correlation among sleep time, body pain, and depressive symptoms. Insufficient sleep time and body pain can lead to depressive symptoms. Body pain plays a partial mediating role between sleep time and depressive symptoms.

Total sleep deprivation effects on the attentional blink

The Attentional Blink (AB) is a phenomenon that reflects difficulty in detecting or identifying the second of two successive targets (T1 and T2) that are presented in rapid succession, between 200-500ms apart. The AB involves indicators of attentional and temporal integration mechanisms related to the early stages of visual processing. The aim of this study was to identify the effects of 24-h of sleep deprivation (total sleep deprivation, TSD) on the attentional and temporal integration mechanisms of the AB. Twenty-two undergraduate students were recorded during five successive days, in these three conditions: baseline (two days), TSD (one day), and recovery (two days). Each day, at around 12:00 h, participants responded to a Rapid Serial Visual Presentation task (RSVP) that presented two targets separated by random intervals from 100 to 1000ms. The attentional mechanisms were assessed by the AB presence, the AB magnitude, and the AB interval, while the temporal integration mechanisms were evaluated by lag-1 sparing and order reversal responses. TSD negatively affected the attentional mechanisms, which is expressed by an overall reduction in performance, an extended AB interval, and a reduced AB magnitude. TSD also negatively affected the temporal integration mechanisms, manifested by an absence of lag-1 sparing and an increase in order reversals. These results suggest that people are still able to respond to two successive stimuli after 24 h without sleep. However, it becomes more difficult to respond to both stimuli because the attentional and temporal integration mechanisms of the AB are impaired.