The hypocretin system consists of two peptides hypocretin-1 and hypocretin-2 (HCRT1 and HCRT2). Hypocretin-containing neurons are located in the posterior and lateral hypothalamus, and have widespread projections throughout the brain and spinal cord. In addition to its presence in the cerebrospinal fluid (CSF), peripheral HCRT1 has been detected in plasma. Robust experimental evidence demonstrates functions of hypothalamic-originated HCRT1 in regulation of multiple biological systems related to sleep–wake states, energy homeostasis and endocrine function. In contrast, HCRT1 studies with human participants are limited by the necessarily invasive assessment of CSF HCRT1 to patients with underlying morbidity.

Regulation by HCRT1 of energy homeostasis and reproduction in animals suggests similar regulation in humans and prompts these two systematic reviews. These reviews translate prior experimental findings from animal studies to humans and examine associations between HCRT1 and: 1) metabolic risk factors; 2) reproductive function in men, women and children. A total of 21 studies and six studies met the inclusion criteria for the two searches, respectively. Research question, study design, study population, assessments of HCRT1, reproductive, cardiometabolic data and main findings were extracted. Associations between HCRT1, metabolic and reproductive function are inconsistent. Limitations of studies and future research directions are outlined.

下丘脑分泌素系统由下丘脑分泌素-1 和下丘脑分泌素-2 两种肽（HCRT1 和 HCRT2）组成。含有下丘脑分泌素的神经元位于下丘脑的后部和外侧，并在整个大脑和脊髓中具有广泛的投射。除了存在于脑脊液 (CSF) 中之外，还在血浆中检测到外周 HCRT1。强有力的实验证据表明，源自下丘脑的 HCRT1 在调节与睡眠-觉醒状态、能量稳态和内分泌功能相关的多个生物系统中具有功能。相比之下，针对人类参与者的 HCRT1 研究受到 CSF HCRT1 对潜在发病患者必然的侵入性评估的限制。

HCRT1 对动物能量稳态和繁殖的调节表明人类也有类似的调节，并促使这两项系统评价。这些综述将先前的动物研究实验结果转化为人类研究，并检查 HCRT1 与以下因素之间的关联：1) 代谢危险因素；2）男性、女性和儿童的生殖功能。共有 21 项研究和 6 项研究分别符合两项检索的纳入标准。提取了研究问题、研究设计、研究人群、HCRT1 评估、生殖、心脏代谢数据和主要发现。HCRT1、代谢和生殖功能之间的关联并不一致。概述了研究的局限性和未来的研究方向。