Intensifying sleep slow oscillations does not improve metabolic control in healthy men

Abstract

Impaired sleep quality and sleep loss compromise glucose homeostasis and metabolic function, but the mechanisms linking sleep and metabolic health are largely unclear. In order to gain insight into the relevance of specific electrophysiological sleep characteristics for metabolic control, we assessed the acute effect on glucose homeostasis as well as energy intake and expenditure of enhancing slow oscillatory activity, a hallmark of slow-wave sleep, by closed-loop auditory stimulation in healthy men. Twenty-two young, normal-weight men underwent an oral glucose tolerance test (oGTT), indirect calorimetry and the assessment of ad-libitum breakfast intake in the morning after nocturnal sleep with or without auditory stimulation in phase with the ongoing rhythmic occurrence of slow oscillation up-states during 210 min of slow-wave sleep in the first night-half. Stimulation vs. no stimulation strongly increased slow oscillatory activity without changing overall sleep structure, but did not alter fasting or oGTT-stimulated measures of glucose homeostasis. Food intake and energy expenditure were likewise comparable between conditions. Findings indicate that in healthy humans electrophysiological sleep quality is tuned to allow for optimal metabolic control. Future studies should investigate the potential of sleep stage-specific interventions to enhance metabolic control and well-being in patients with metabolic ailments.

Closed-loop auditory stimulation of sleep slow oscillations: basic principles and best practices

“…Interestingly, previous studies in humans have found that while slow-wave activity could be acutely boosted during stimulation trials or periods, these increases often seemed to level out over the entire night (Ngo et al, 2013;Papalambros et al, 2017;Schneider et al, 2020), which would hint at an inherent limit of SO activity that the brain is willing to engage in. Contrarily, enhancing total night SWA was possible in other studies (Diep et al, 2020;Garcia-Molina et al, 2018;Santiago et al, 2019) and may therefore be conditional on specific stimulation parameters. Thus, the question of whether 'more' stimulation appears to entail better effects, and if so of what nature, has yet to be conclusively answered.…”

“…The majority of CLAS studies employed a continuous timing protocol for stimuli presentation (Besedovsky et al, 2017;Cox et al, 2014;Diep et al, 2020;Henin et al, 2019;Leminen et al, 2017;Ngo et al, 2013Ngo et al, , 2015Ngo et al, 2018;Santiago et al, 2019), while some others performed stimulation timing in a blockwise manner (Fattinger et al, 2019;Ong et al, 2016Ong et al, , 2018Papalambros et al, 2017Papalambros et al, , 2019. Figure 2 schematically represents the differences between the continuous and the block-wise stimulation timing.…”

“…Various studies showed that CLAS is a promising technique in clinical research and might potentially be used as a therapy in patients with endocrine or immune system deficits (Besedovsky et al, 2017;Grimaldi et al, 2019;Santiago et al, 2019). In this section, we inspect the potential applicability of CLAS for clinical usage.…”

The Potential Role of Sleep in Promoting a Healthy Body Composition: Underlying Mechanisms Determining Muscle, Fat, and Bone Mass and Their Association with Sleep

“…Even though this method is still in its infancy, some well-controlled in-lab studies exist, which showed its potential in boosting slow waves along with modifications in memory consolidation, cortisol levels [95], and immune supportive responses [95]. Single session glucose tolerance and GH levels in healthy young adults were not effectively modulated so far [95, 392]. However, further research over longer time periods and in populations/situations of increased metabolic demand (e.g., elderly, athletes, and obese) is essential to evaluate its potential to modulate certain metabolic pathways.…”

Commentary: SWS Brain-Wave Music May Improve the Quality of Sleep: An EEG Study

“…These results suggest that the reduction of delta power is instead indicative of an impairment. This view results from both the positive consequences of increasing delta power and the negative consequences of prolonged delta power reduction (both clinically and cognitively), which is why research has focused on increasing delta power for optimal sleep quality (Marshall et al, 2006;Santiago et al, 2019).…”