Elucidate the brain structures and neurotransmitters/hormones involved in initiating/maintaining sleep and those involved in waking/arousal. Explain insomnia from a neurobiological perspective.
Response Parameters
Initial Post
- Each initial post should include a minimum of 250 words of actual text (i.e., the 250 word minimum does not include your reference)
- At least 1 outside, empirical/peer-reviewed reference should be integrated in your initial post (your textbook and the lecture do not count as an outside source). Failure to include an outside source will result in a grade of 0.
- Correct APA formatting of citations/references is required and part of your grade
- Point value: 15 points
Brain Structures and Neurotransmitters/Hormones in Sleep and Wakefulness
Sleep and wakefulness are complex processes regulated by various brain structures, neurotransmitters, and hormones. The primary brain structures involved in initiating and maintaining sleep include the hypothalamus, thalamus, and brainstem. The hypothalamus contains the suprachiasmatic nucleus (SCN), which is crucial for regulating circadian rhythms and sleep-wake cycles. The SCN influences the pineal gland to release melatonin, a hormone that promotes sleepiness, especially in dim light conditions (Brown et al., 2012).
The thalamus plays a role in filtering sensory information during sleep, particularly during non-REM sleep. The brainstem, including the pons and medulla, helps regulate the transition between sleep stages and REM sleep (Brown et al., 2012).
Neurotransmitters and hormones involved in sleep include gamma-aminobutyric acid (GABA), serotonin, and melatonin. GABA, an inhibitory neurotransmitter, plays a key role in promoting sleep by reducing neuronal excitability. Serotonin, synthesized in the raphe nuclei, is involved in regulating sleep-wake cycles, particularly in promoting sleep onset (Monti, 2011). Melatonin, produced by the pineal gland, is crucial for signaling sleep and maintaining circadian rhythms.
In contrast, wakefulness and arousal are regulated by brain structures such as the reticular activating system (RAS) in the brainstem, the hypothalamus, and the basal forebrain. The neurotransmitters involved in wakefulness include norepinephrine, dopamine, acetylcholine, and orexin (hypocretin). Norepinephrine and dopamine are involved in promoting alertness and arousal by activating the RAS and other cortical areas. Acetylcholine and orexin are also key neurotransmitters that maintain wakefulness and prevent the onset of sleep (Saper et al., 2010).
Neurobiological Perspective on Insomnia
Insomnia, characterized by difficulty falling or staying asleep, can be understood from a neurobiological perspective as a dysregulation of the sleep-wake systems. In individuals with insomnia, there is often an imbalance between the arousal-promoting and sleep-promoting systems. For example, heightened activity in the hypothalamic-pituitary-adrenal (HPA) axis leads to increased cortisol levels, which can inhibit sleep onset and maintenance. Additionally, abnormalities in the function of the RAS, leading to excessive arousal, have been implicated in insomnia. Dysregulation in neurotransmitter systems, such as reduced GABA activity or altered orexin levels, can also contribute to difficulties in initiating and maintaining sleep (Riemann et al., 2010).
Overall, insomnia is a multifaceted condition that involves complex interactions between brain structures, neurotransmitters, and hormones, reflecting an imbalance in the neurobiological systems regulating sleep and wakefulness.
References
Brown, R. E., Basheer, R., McKenna, J. T., Strecker, R. E., & McCarley, R. W. (2012). Control of sleep and wakefulness. Physiological Reviews, 92(3), 1087-1187. https://doi.org/10.1152/physrev.00032.2011
Monti, J. M. (2011). Serotonin control of sleep-wake behavior. Sleep Medicine Reviews, 15(4), 269-281. https://doi.org/10.1016/j.smrv.2010.11.003
Riemann, D., Spiegelhalder, K., Espie, C., Pollmächer, T., Léger, D., Bassetti, C., & Van Someren, E. (2010). Chronic insomnia: Clinical and research challenges—an agenda. Journal of Sleep Research, 20(1pt2), 123-131. https://doi.org/10.1111/j.1365-2869.2010.00870.x
Saper, C. B., Scammell, T. E., & Lu, J. (2010). Hypothalamic regulation of sleep and circadian rhythms. Nature, 437(7063), 1257-1263. https://doi.org/10.1038/nature04284