Physiological Basis of Sleep: Adaptation of bodily functions to sleep
For this Sleep Science Friday, we bring you another chapter summary from the ESRS Sleep Medicine Textbook 2nd edition, “Adaptation of bodily functions to sleep” from the section Physiological Basis of Sleep.
Adaptation of bodily functions to sleep
Behavioural states can be identified according to the value of different physiological variables, driven by the integrated activity of the somatomotor, autonomic, and endocrine systems. This integration mostly occurs at the hypothalamic level. Therefore, the physiological definition and understanding of wake-sleep states is possible only through the assessment, during the different states, of the respiratory, cardiovascular, and metabolic parameters, and the responses elicited by internal or external stimuli challenging the different physiological regulatory mechanisms. This goes far beyond the standard definition of the wake-sleep (WS) states, substantially based on the level of brain cortical and somatomotor activity. According to this, non-rapid eye movement (NREM) sleep can be defined as a state of minimal energy expenditure and motor activity, during which cardiovascular, respiratory, and thermoregulatory variables are driven by the autonomic nervous system at a lower level compared with wakefulness, and are kept stable by the autonomic reflexes. During NREM sleep, physiological regulation is clearly operant for the maintenance of body homeostasis. On the contrary, during REM sleep, posture control is lost, autonomic activity is highly unstable, centrally driven surges in heart rate and blood pressure occur, breathing becomes irregular, and thermoregulation is suspended or depressed. Such an operative modality of physiological regulation has been defined as “poikilostatic,” and is attributed to a derangement of the integrative function of the hypothalamus during REM sleep. However, recent data showing that osmoregulation is maintained during REM sleep suggest that such a derangement is not extended to the whole hypothalamus.
Keywords:
autonomic functions, cardio-respiratory functions, endocrine functions, physiological regulation, sensory-motor functions, thermoregulation
Learning Objectives:
- The reader identifies sleep states not only based on the values of electroencephalogram rhythms and muscle activity, but also through the assessment of the respiratory, cardiovascular, and metabolic parameters.
- The reader appraises the relevance of the impact of autonomic activation on sleep occurrence.
- The reader evaluates the cruciality of the link between REM sleep and thermoregulation.
Key Points:
- Non-rapid eye movement (NREM) sleep is a state of minimal energy expenditure and motor activity during which cardio-respiratory and thermoregulatory variables are driven by the autonomic nervous system at a lower and more stable level compared with wakefulness.
- During rapid eye movement (REM) sleep, posture control is lost, autonomic activity is highly unstable, centrally driven surges in heart rate and blood pressure occur, breathing becomes irregular, and thermoregulation is suspended or depressed.
- … you can read all key points and the full A.3 Adaptation of bodily functions to sleep chapter in the ESRS Sleep Medicine Textbook – order it here.
Summary by:
Roberto Amici and Giovanna Zoccoli (2021). A. Physiological Basis of Sleep 3. Adaptation of bodily functions to sleep. In Bassetti, C., McNicholas, W., Paunio, T., & Peigneux, P. (Eds.). Sleep Medicine Textbook (2nd ed., pp. 27-38). Regensburg: European Sleep Research Society.
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