People who stay up later than intended may have a weaker physiological capacity for self-control. A new study published in the Journal of Health Psychology links lower heart rate variability to greater bedtime procrastination.
Many individuals experience the temptation to prolong their use of digital devices, or complete further tasks, despite being aware that they should already be asleep—a behavior known as bedtime procrastination. Scientists have previously connected bedtime procrastination to difficulties with managing behavior and emotions. Individuals who struggle to prioritize long-term wellbeing over short-term enjoyment, or who have trouble regulating negative feelings, are thought to be more prone to pushing their bedtime later.
What has been less well understood is whether this tendency also has a measurable biological marker. A promising candidate is heart rate variability (HRV), defined as the natural variation in the time between heartbeats. Previous research has demonstrated that a higher level of this variability—particularly the component driven by the body’s calming “rest and digest” nervous system (the vagus nerve)—is associated with adaptability to stress and a greater capacity for self-control.
Hence, the researchers in the present study sought to examine whether this physiological marker, alongside self-reported difficulties with managing behavior and emotions, could predict how much someone tends to procrastinate at bedtime.
Lena Mareen Grabo and Silja Bellingrath of the University of Duisburg-Essen in Germany recruited 135 adults aged between 18 and 82 (with an average age of around 29; approximately 65% female). Participants first sat quietly for ten minutes while their heart rate was continuously measured using an accurate chest strap device. From this recording, the researchers calculated each person’s baseline level of heart rate variability.
Participants also filled out questionnaires reporting on how often they procrastinate at bedtime, how well they manage their own behavior and emotions, and how often they engage in specific thinking styles. These thinking styles included a tendency to “brood” (getting stuck in passive, repetitive, negative thought loops) versus “reflect” (purposefully thinking through problems to solve them).
The results pointed to a clear picture in which bedtime procrastination reflects challenges across multiple different aspects of self-control simultaneously. Individuals scoring higher on bedtime procrastination tended to have lower heart rate variability, greater difficulty regulating their behavior, and greater difficulty managing their emotions. Importantly, each of these three factors contributed independently to the prediction of bedtime procrastination.
When analyzing the specific ways people deal with emotions, a nuanced picture emerged. While using “cognitive reappraisal” (a deliberate strategy of reframing stressful situations in a more positive light) initially appeared to reduce bedtime procrastination, it lost its predictive power when other emotional habits were factored in. Ultimately, only “brooding” significantly predicted procrastinating at bedtime in the final model. Conversely, engaging in more reflective, problem-focused thinking did not show any link to delaying sleep.
The study also found that bedtime procrastination was moderately associated with both shorter sleep duration and worse sleep quality, reinforcing just how consequential this habit can be for nightly rest.
Interestingly, the study found no significant connection between a person’s biological heart rate variability and their self-reported measures of behavioral and emotional regulation. This suggests the different components of the self-control system operate somewhat independently, even though they all contribute to the same behavioral outcome.
“Taken together, the findings highlight bedtime procrastination as a problem of diminished self-regulatory capacity reflected in both physiological (lower heart rate variability) and psychological (poorer behavioral and emotion regulation) domains, yet they also suggest that self-regulation is not a unitary construct,” Grabo and Bellingrath concluded.
Some limitations should be noted. For example, the study was conducted at one point in time, and the researchers caution that it cannot reveal strict causality. It is possible that low self-control causes bedtime procrastination, which causes poor sleep, which in turn further depletes self-control the next day in a bidirectional loop.
The study, “Bedtime procrastination as a typical problem of self-regulation? Insights from the examination of heart rate variability, behavioral regulation and emotion regulation,” was authored by Lena Mareen Grabo and Silja Bellingrath.