The effects of acupuncture on sleep disorders and its underlying mechanism: a literature review of rodent studies

Sleep is an essential function that occupies about 20 to 40% of our day and represents a set of complex physiologic processes regulated by the nervous system, affecting various body systems. When these normal sleep patterns are disturbed, sleep disorders develop, which can include insomnia, sleep-related breathing disorders, excessive sleepiness, circadian rhythm alterations, and other movement-related sleep problems. These disorders are associated with serious health consequences such as obesity, cardiovascular disease, mental health problems, and neurodegenerative diseases such as Alzheimer disease and Parkinson disease. Although several methods exist to treat sleep disorders, many lack adequate efficacy and present safety concerns, creating the need to explore safe and effective alternative treatments.

Acupuncture, a therapy based on the insertion of needles at specific points on the body, has shown clear evidence of efficacy in Western medicine. Clinical studies have already confirmed that acupuncture can improve both the duration and quality of sleep, in addition to benefiting the psychological health of patients with insomnia. Acupuncture treatment demonstrates positive effects particularly in neurologic conditions, influencing neurotransmitters and their receptors, increasing dopamine and GABA levels, while decreasing glutamate levels. This study aimed to investigate the mechanisms by which acupuncture exerts its beneficial effects on sleep disorders, using animal models to better understand how this therapy works at the brain level.

The investigators conducted a systematic review of the scientific literature, searching for English-language studies that investigated the effects of acupuncture on sleep disorders using animal models. The search was performed in major medical databases through April 2023, using keywords related to acupuncture, electroacupuncture, mice, rats, and sleep disorders. Only studies that used animal models of sleep disorders and that evaluated the effects of acupuncture through electroencephalograms and analyses of brain mechanisms were included. After rigorous screening of 43 initially identified studies, 17 studies were selected for final analysis.

Methodologic quality of the studies was assessed using specific tools for animal research, examining aspects such as randomization, control conditions, and risks of bias. Most studies used rats as an animal model, with electroacupuncture being the most frequently employed intervention.

The results revealed that acupuncture acts through multiple brain mechanisms to improve sleep disorders. Treatment was shown to influence several brain regions important for sleep regulation, including the hippocampus, hypothalamus, prefrontal cortex, pineal gland, brainstem, and medial septum. Acupuncture showed significant effects on the regulation of essential neurotransmitters for sleep, such as serotonin, dopamine, norepinephrine, GABA, and acetylcholine. Particularly important was the discovery that acupuncture influences BDNF (brain-derived neurotrophic factor), a protein crucial for neuronal protection and brain plasticity.

Studies showed that different acupuncture techniques, including manual acupuncture, electroacupuncture, and warm acupuncture, activated several important cellular signaling pathways, such as TrkB, PI3K/Akt, and cAMP/CREB/BDNF pathways. Among the acupuncture points used, point HT-7 was the most frequently employed, demonstrating neuroprotective effects in several models of neurologic conditions.

For patients suffering from sleep disorders, these findings offer a solid scientific basis for considering acupuncture as a safe and effective therapeutic option. The research demonstrates that acupuncture not only improves sleep symptoms but acts on the fundamental brain mechanisms that regulate the sleep-wake cycle. For health care professionals, these results provide evidence on how acupuncture can be integrated into the treatment of sleep disorders, especially considering that many conventional treatments have limitations in terms of efficacy and safety. The discovery that different acupuncture points activate specific mechanisms suggests that personalized treatment protocols can be developed based on each patient's particular condition.

The fact that acupuncture positively influences neurotransmitters such as serotonin and GABA, known for their roles in mood and relaxation regulation, also suggests potential benefits beyond improvement in sleep.

It is important to recognize some limitations of this research that should be considered in interpreting the results. The study included only 17 investigations, representing a relatively small sample, and all studies were conducted in animal models, primarily rats. Although animal models provide valuable information on biological mechanisms, the results cannot be directly extrapolated to humans without appropriate clinical studies. In addition, the analyzed studies used different types of acupuncture, application points, and treatment durations, making it difficult to establish standardized protocols.

The methodologic quality of some studies presented limitations, including lack of information on investigator blinding and details about acupuncture procedures. Despite these limitations, this review represents an important step toward understanding the neurobiological mechanisms by which acupuncture benefits sleep disorders, providing a solid foundation for future clinical research and the development of more effective treatment protocols for patients seeking safe, evidence-based therapeutic alternatives.