Today we have Dr. Hans Van Dongen, director of the Sleep and Performance Research Center at Washington State University in Spokane. Dr. Kevin Gluck, a senior research scientist at IHMC, joins Dr. Ken Ford to interview Hans about his studies on inter-individual differences in vulnerability to fatigue as well as the cumulative cognitive deficits that follow chronic sleep restriction. Hans is known for his mathematical modeling of fatigue’s effects on performance. At the Sleep and Performance Research Center, Hans and his colleagues investigate how sleep loss and circadian misalignment impact brain function, cognition and behavior. Show notes: [00:02:50] Kevin opens the interview by asking Hans about his childhood growing up in The Netherlands. [00:03:23] Ken asks Hans what he was like as a kid. [00:03:50] Kevin mentions Hans’s father was a math and science teacher and wonders if that influenced Hans’ interest in science. [00:04:48] Hans talks about attending Leiden University and explains why he majored in astrophysics. [00:06:09] Hans shares how working in a psychophysiology lab put him on a path to specialize in sleep research. [00:08:00] Hans talks about how he was part of a study that proved the morning-evening chronotype was a biological trait, rather than a psychological one. [00:09:55] Ken asks Hans what led him to take a post-doc position at the University of Pennsylvania. [00:11:22] Hans explains what led him to move from the University of Pennsylvania to Washington State University. [00:13:36] Ken mentions that The Sleep and Performance Research Center, where Hans serves as the director, is a coalition of basic and applied research laboratories that aim to understand the neurobiology of sleep and sleep loss. Ken goes on to mention that Hans and his colleagues investigate sleep and biological rhythms, and their impact on health and performance. Kevin asks Hans to give an overview of what sleep loss is and the effect it has on our metabolism, immune system, and cognitive performance. [00:15:57] Kevin mentions Hans’ recent paper which investigated how circadian misalignment due to night shift work has been associated with an elevated risk of chronic disease. The paper demonstrated that just a few days of being on a night shift schedule throws off protein rhythms related to blood glucose regulation, energy metabolism, and inflammation. Kevin asks Hans to talk more about the findings. [00:21:18] Ken asks how long it takes for a person’s circadian rhythm to normalize after ceasing to work night shifts. [00:22:13] Kevin brings up Hans’ paper on the continually operating neurobiological mechanisms of homeostatic and circadian processes and their effects on neurobehavioral performance. Before asking about the paper itself, Kevin asks Hans to give an overview of the homeostatic process and its relationship to the circadian process. [00:24:14] Ken notes that the bio-behavioral function and evolutionary advantage of the circadian process is widely recognized, but that the neurobiology of the homeostatic process and its effects on performance are still poorly understood. In a 2011 paper, Hans attempted to shed light on the underlying mechanisms of the homeostatic process to provide an explanation for why the buildup of homeostatic pressure resulting from sleep loss leads to instability in vigilant attention. To explore this, Hans first explored the time-on-task effect. Ken asks Hans to explain the time-on-task effect and its role in cognitive performance. [00:27:06] Kevin brings up the “local sleep hypothesis,” which attempts to explain the time-on-task effect. According to the local sleep hypothesis, groups of neurons involved in performing a task will “fall asleep” as a homeostatic consequence of sustained use, which leads to an interruption in information processing, leading to impaired performance. Kevin asks Hans what empirical and scientific evidence exists for the hypothesis...