**📅 Date:** ➤ ⌈[[2025-04-09-Wed〚 🧠 Suprachiasmatic Nucleus（视交叉上核） 〛]]⌋ >[!info] The **SCN is the conductor** of your body’s biological symphony. Keeping it in rhythm = better sleep, mood, metabolism, and healthspan. ⇩ 🅻🅸🅽🅺🆂 ⇩ **🏷️ Tags**: #🧠/Neuro-Science **🗂 Menu**: ⌈[[✢ M O C ➣ 04 ⌈A P R - 2 0 2 5⌉ ✢|2025 - A P R- MOC]]⌋ ⌈[[✢ L O G ➢ 04 ⌈A P R - 2 0 2 5⌉ ✢|2025 - A P R - LOG]]⌋ #👾/Private ➤ ⌈[[Jet Lag Interventions]]⌋ ➤ ⌈[[Circadian Misalignment — What It Is & How to Fix It]]⌋ --- ### 🌟 What is the Suprachiasmatic Nucleus (SCN)? ![[Pasted image 20250422021942.png]] **SCN（视交叉上核）** 是大脑中掌管昼夜节律（circadian rhythm）的“主时钟”。 - Located in the **hypothalamus**（下丘脑）, just above the **optic chiasm**（视交叉）. - Contains ~20,000 neurons that **synchronize the body's internal clock** to the **light-dark cycle**. - It controls **melatonin** secretion from the pineal gland and **regulates sleep-wake cycles**, body temperature, hormone release, and even metabolism. --- ### 🧠 Key Functions | **Function** | **Description** | |--------------------------|----------------------------------------------------------------------------------| | ⏰ Master Clock | Coordinates circadian rhythms across tissues and organs | | ☀️ Light Sensitivity | Receives direct input from **retinal photoreceptors** through the **retinohypothalamic tract** | | 🌙 Melatonin Regulation | Signals pineal gland to secrete melatonin in darkness, suppressed by light | | 🔄 Rhythm Synchronization| Syncs peripheral clocks in liver, gut, muscle, etc. | --- ### 🔬 Scientific Highlights - **Disruption of SCN** leads to: - Insomnia or sleep phase disorders - Jet lag symptoms - Mood dysregulation - Hormonal imbalance - **Melatonin supplements** work by mimicking SCN's timing signals. - **Blue light** at night suppresses SCN-driven melatonin production ➤ disrupted sleep. --- ### ✈️ SCN & Jet Lag - When we travel across time zones, our **SCN is misaligned** with the external environment. - Takes 1–2 days per time zone to fully realign. - Strategic light exposure, fasting, and melatonin can help re-entrain the SCN. --- ### 🧪 Research & Longevity Notes - SCN deterioration is associated with **aging** and **neurodegenerative disorders**. - Supporting **robust circadian rhythms** can enhance sleep quality, metabolic health, and cognitive resilience. - Studies show **caloric restriction and time-restricted feeding** can enhance SCN function and overall circadian rhythm stability. --- ### 🛠️ Biohacker’s Toolkit for SCN Optimization - ☀️ **Morning light** exposure within 30 min of waking - 🌙 **Dim lights** after sunset & use **blue-light filters** - 🕐 **Consistent sleep-wake time**, even on weekends - 🍽️ **Avoid late-night eating** to align gut clocks with SCN - 💊 Use **melatonin (0.3–1mg)** only when needed (e.g., jet lag)