Currently selected for this coming member’s digest by team member Melisa B.

Getting an adequate amount of quality sleep is increasingly recognized as vital for mental and physical health. Sleep deprivation can increase stress hormones associated with anxiety and depression and greater risk of chronic diseases like cardiovascular disease. A recent randomized trial found that a night of sleep deprivation can impair a person’s ability to ignore intrusive thoughts.

Intrusive thoughts include unpleasant memories, images, or worries that are difficult to ignore or suppress. These types of thoughts can cause low mood and difficulty focusing on important tasks. They are common features of mental illnesses such as major depressive order and post-traumatic stress disorder.

Poor sleep impairs brain function through a number of mechanisms such as influencing heart rate variability, the variation in time between heart beats. Low heart rate variability indicates greater fight-or-flight response by the autonomic nervous system and is associated with an increased cardiovascular disease risk. Poor sleep is known to decrease heart rate variability.

The investigators trained a group of 60 participants to associate a set of emotionally negative and neutral scenes with human faces. Then they assigned participants to a night of normal sleep or total sleep deprivation. The next morning participants completed a task called “Think/No Think,” where they were shown a face from the previous day and asked to recall or suppress the scene associated with that face. Their ability to control memory retrieval and suppression was self-reported. The investigators also measured heart rate variability before the task using electrocardiography.

Participants in the sleep deprivation group reported that they were unable to suppress intrusive thoughts about 50 percent more often than the control group. The authors define intrusive thoughts as memories of scenes from the previous day that the researchers asked participants to suppress during the task. For participants in the well-rested group, higher heart rate variability was predictive of better intrusive thought suppression.

Normally, the prefrontal cortex controls areas of the brain important emotional regulation, the amygdala, and memory, the hippocampus. The authors suggested the intrusive thoughts experienced by sleep-deprived participants are caused by an increase in fight-or-flight response and subsequent loss of control by the prefrontal cortex, a hypothesis supported by existing literature. They advised that future research should include brain imaging to confirm these results.

• Link to full study.

• Learn more about the role that sleep plays in health in this podcast featuring sleep expert Dr. Matthew Walker.