如何利用冷热暴露改善健康
摘要
Susanna Søberg博士在哥本哈根大学完成了她的博士研究，本文探讨了主动冷暴露和热暴露背后的科学原理，以及它们对新陈代谢、棕色脂肪激活、神经递质产生和长期健康结果的影响。她于2021年发表在《Cell Reports Medicine》上的里程碑式研究，确立了冷热暴露产生有意义生理变化所需的最低有效阈值。对话内容涵盖从冷休克反应到结合桑拿和冷水浸泡的具体方案等各个方面。
核心要点
- 任何令人不适的冷暴露——冷水浸泡、冷水淋浴、冷空气，甚至冷风——都足以激活棕色脂肪组织并触发有益的代谢反应。
- 颤抖是有益的，不应刻意避免；它能激活棕色脂肪、燃烧卡路里，并通过健康的细胞应激（毒物兴奋效应）改善胰岛素敏感性。
- 冷热交替训练以冷结束（即”Søberg原则”），通过强迫身体利用棕色脂肪产热进行自我复温，从而最大化代谢收益。
- 冷休克反应——过度换气、喘息、心率升高——会随着反复暴露而减弱，因为身体会逐渐适应；这种适应是一种特性，而非缺陷。
- 在19°C的房间中睡眠一个月，已被证实可增加棕色脂肪体积并改善胰岛素敏感性，无需进行水中浸泡。
- 长期冷暴露与较低的血压、较低的静息心率以及改善的胰岛素敏感性相关——这些指标有助于降低心血管疾病和代谢疾病的风险。
- 棕色脂肪具有高度可塑性：可随反复冷暴露而增长，也可随长期处于温暖环境而退化；即便进入老年，尤其是经常在户外工作或活动的人群，棕色脂肪仍可被激活。
- 女性的棕色脂肪多于男性，其感到热舒适的室温约比男性高2°C，这对研究设计和方案个性化具有重要意义。
- 所研究的最低有效方案为每周2–3次训练，每次冷水浸泡1–2分钟，每次训练进行三轮冷暴露，与约80°C的桑拿交替进行，桑拿时间约10–15分钟。
详细笔记
进入冷水时身体会发生什么生理变化
当身体浸入冷水时，皮肤中的冷感受器会迅速向下丘脑发出信号，触发：
- 交感神经系统激活
- 儿茶酚胺急剧升高：去甲肾上腺素、肾上腺素和多巴胺
- 冷休克反应：过度换气、喘息反射、心率和血压升高
- 外周血管收缩以保护核心体温
如果进入冷水前身体已经处于温热状态（例如刚离开桑拿），由于皮肤处的温差较小，冲击感会相对较弱。随着反复暴露，冲击反应会逐渐减弱——过度换气消退，对冷的耐受性提高，抗压能力增强。
冷暴露方式：有效性比较
| 方式 | 冷感受器激活程度 | 棕色脂肪激活程度 | 备注 |
|---|---|---|---|
| 冷水浸泡（至颈部） | 非常高 | 强 | 研究最多；效力最强 |
| 冷水淋浴 | 中等 | 可能有效 | 研究较少；难以控制变量 |
| 冷空气 / 在冷风中穿T恤 | 较低 | 存在 | 激活交感神经系统；适合日常使用 |
| 将面部浸入冰水 | 高（面部感受器） | 存在 | 激活潜水反射 |
| 在19°C环境中睡眠 | 低但持续 | 有记录的增长 | 一个月即足以促进棕色脂肪增长 |
关键点： 冷水浸泡使更大面积的体表与水分子紧密接触，产生比冷空气更快速、更强效的自主神经反应。然而，即便是冷空气也能激活去甲肾上腺素释放和棕色脂肪产热。
棕色脂肪：生物学特性与功能
棕色脂肪组织（BAT）与白色脂肪的区别在于其高密度的线粒体，这赋予了它独特的颜色，并使其能够产生热量（非颤抖性产热）。
在体内的分布位置：
- 主要位于锁骨上区域（锁骨下方）、上背部及脊柱周围
- 靠近皮肤表面——可通过红外热成像仪进行测量
- 人体中已确认至少六个棕色脂肪储库；其分布比此前认为的更为广泛
主要特性：
- 高度可塑性：可增长（线粒体增殖、细胞体积增大）也可退化
- 主要由寒冷和去甲肾上腺素激活
- 作为温度变化的”第一响应者”——反应速度快于骨骼肌颤抖
- 从血液中摄取葡萄糖和游离脂肪酸为产热提供燃料，从而直接改善胰岛素敏感性和血糖调节
三条并行激活通路：
- 皮肤冷感受器 → 下丘脑 → 去甲肾上腺素释放 → 棕色脂肪激活
- 直接通路：皮肤冷感受器 → 棕色脂肪（绕过中枢处理）
- 骨骼肌颤抖 → 通过琥珀酸信号进一步激活棕色脂肪
与衰老和肥胖的关联：
- 棕色脂肪活性通常在40岁以后下降
- 与胰岛素抵抗增加和肥胖相关——尽管因果关系尚不明确（是棕色脂肪减少导致肥胖，还是肥胖导致棕色脂肪减少？）
- 长期从事户外体力工作的人往往能在年老后保持更多的棕色脂肪
颤抖的作用
颤抖性产热是对寒冷的继发性代谢反应：
- 发生在后降温阶段——离开冷水后，由于血管收缩解除，较冷的外周血液回流至核心，核心体温会持续下降
- 颤抖会提升新陈代谢、燃烧卡路里并激活棕色脂肪
- 在肌肉细胞中产生毒物兴奋效应性应激，增加热休克蛋白含量，提升细胞鲁棒性
- 改善胰岛素敏感性是反复诱发颤抖的冷暴露所记录的效果之一
实践提示： 冷暴露后不要急于取暖，颤抖反应是获益机制的重要组成部分。
Søberg研究：设计与方案
研究对象： 男性冬泳爱好者，已具备适应性（2–3个先前泳季），在BMI和饮食方面与久坐对照组相匹配。
每次训练方案：
- 3轮冷水浸泡（每轮1–2分钟）
- 2次桑拿（约10–15分钟，温度约80°C）
- 冷热交替顺序：冷 → 桑拿 → 冷 → 桑拿 → 冷
- 始终以冷结束
频率： 每周2–3次
水温： 户外海水，随季节变化而偏冷（具体温度有所不同）
主要测量指标： 通过PET-CT扫描评估棕色脂肪激活情况
关键发现： 该方案——代表最低有效剂量——足以增加棕色脂肪活性、改善葡萄糖代谢，并产生可测量的代谢益处。
Søberg原则：以冷结束
训练以冷结束（而非之后在桑拿或热水淋浴中复温）能迫使身体利用棕色脂肪产热自主产生热量。这是代谢收益得以巩固的核心机制。
- 冷水浸泡后立即冲热水澡会使这一过程短路
- 身体的自主复温本身就是训练棕色脂肪的刺激信号
主动冷暴露的长期健康益处
基于所引用的研究及Søberg博士本人的研究：
- 静息血压降低
- 静息心率降低
- 胰岛素敏感性改善及血糖调节优化
- 炎症标志物减少
- 儿茶酚胺水平升高（多巴胺、去甲肾上腺素）——效果可在暴露后持续数小时
- 体温调节改善——在寒冷环境中无需额外添衣即可感到更为舒适
- 心理健康：血清素升高、情绪改善、暴露后精力充沛、积极情绪增加（基于问卷调查；尚需机制性研究支持）
冷适应与实践入门
对于冷暴露新手，循序渐进的方式如下：
- 在较凉爽的房间睡眠（约19°C）——入门容易，益处有据可查
- 秋冬户外活动时减少衣物层数
- 冷水淋浴——研究相对较少，但可能对棕色脂肪激活有效
- 冷水浸泡（冷水浴桶、开放水域）——最强效的刺激方式
无需极长的时间。一到两分钟令人不适的冷暴露即已
English Original 英文原文
How to Use Cold & Heat Exposure to Improve Your Health
Summary
Dr. Susanna Søberg, who completed her doctoral research at the University of Copenhagen, discusses the science behind deliberate cold and heat exposure and their effects on metabolism, brown fat activation, neurotransmitter production, and long-term health outcomes. Her landmark 2021 study in Cell Reports Medicine established minimum effective thresholds for cold and heat exposure to drive meaningful physiological changes. The conversation covers everything from the cold shock response to specific protocols for combining sauna and cold immersion.
Key Takeaways
- Any uncomfortable cold exposure — cold plunge, cold shower, cold air, or even cold wind — is sufficient to activate brown adipose tissue and trigger beneficial metabolic responses.
- Shivering is beneficial, not something to avoid; it activates brown fat, burns calories, and improves insulin sensitivity through healthy cellular stress (hormesis).
- End cold-heat sessions on cold (the “Søberg Principle”) to maximize metabolic benefits by forcing the body to self-reheat using brown fat thermogenesis.
- The cold shock response — hyperventilation, gasping, elevated heart rate — subsides with repeated exposure as the body adapts; this adaptation is a feature, not a bug.
- Sleeping in a room at 19°C for one month has been shown to increase brown fat volume and improve insulin sensitivity, with no need for immersion.
- Long-term cold exposure is associated with lower blood pressure, lower resting heart rate, and improved insulin sensitivity — markers that reduce risk of cardiovascular and metabolic disease.
- Brown fat is highly plastic: it can grow with repeated cold exposure and shrink with prolonged warmth; it remains activatable into older age, especially in people who work or move outdoors.
- Women have more brown fat than men and are thermally comfortable at approximately 2°C warmer room temperatures, which has implications for study design and protocol personalization.
- The minimum effective protocol studied was 2–3 sessions per week, with cold immersion of 1–2 minutes per dip, three rounds of cold per session, alternated with ~10–15 minutes of sauna at ~80°C.
Detailed Notes
What Happens Physiologically When You Enter Cold Water
When the body is submerged in cold water, cold receptors in the skin rapidly signal the hypothalamus, triggering:
- Activation of the sympathetic nervous system
- A sharp rise in catecholamines: norepinephrine, epinephrine, and dopamine
- Cold shock response: hyperventilation, gasping reflex, elevated heart rate and blood pressure
- Vasoconstriction in peripheral blood vessels to protect core temperature
If you are already warm (e.g., coming from a sauna), the shock is perceived as less intense because the thermal differential at the skin is reduced. With repeated exposure, the shock response diminishes as the body adapts — the hyperventilation subsides, cold becomes more tolerable, and resilience builds.
Cold Modalities: Comparing Effectiveness
| Modality | Cold Receptor Activation | Brown Fat Activation | Notes |
|---|---|---|---|
| Cold immersion (to neck) | Very high | Strong | Most studied; most potent |
| Cold shower | Moderate | Likely effective | Fewer studies; harder to control |
| Cold air / t-shirt in cold wind | Lower | Present | Activates sympathetic NS; practical for daily use |
| Submerging face in ice water | High (face receptors) | Present | Activates dive reflex |
| Sleeping at 19°C | Low but sustained | Documented increase | One month sufficient to grow brown fat |
Key point: Cold immersion covers more body surface area with molecules closer to skin, producing a more rapid and potent autonomic response than cold air. However, even cold air activates norepinephrine release and brown fat thermogenesis.
Brown Fat: Biology and Function
Brown adipose tissue (BAT) differs from white fat in its high mitochondria density, which gives it its color and enables heat production (non-shivering thermogenesis).
Location in the body:
- Primarily in supraclavicular region (under collarbone), upper back, and around the spine
- Close to the skin surface — measurable via infrared thermography
- At least six depots identified in humans; distribution is more widespread than previously thought
Key properties:
- Highly plastic: can grow (hyperplasia of mitochondria, increased cell volume) and regress
- Activated primarily by cold and norepinephrine
- Acts as a “first responder” to temperature change — faster than skeletal muscle shivering
- Takes up glucose and free fatty acids from the bloodstream to fuel thermogenesis, directly improving insulin sensitivity and blood glucose regulation
Three parallel activation pathways:
- Cold receptors in skin → hypothalamus → norepinephrine release → brown fat activation
- Direct pathway: cold skin receptors → brown fat (bypassing central processing)
- Shivering in skeletal muscle → additional brown fat activation via succinate signaling
Association with aging and obesity:
- Brown fat activity tends to decrease after age 40
- Associated with increased insulin resistance and obesity — though causality is unclear (does less BAT cause obesity, or does obesity reduce BAT?)
- People who work outdoors physically tend to maintain more brown fat into older age
The Role of Shivering
Shivering thermogenesis is a secondary metabolic response to cold:
- Occurs as the after drop — when core body temperature continues to fall after exiting cold water because vasoconstriction releases and cool peripheral blood returns to the core
- Shivering increases metabolism, burns calories, and activates brown fat
- Produces hormetic stress in muscle cells, increasing heat shock proteins and cellular robustness
- Improving insulin sensitivity is one documented outcome of repeated shiver-inducing cold exposure
Practical note: Do not rush to warm up after cold exposure. The shiver response is part of the beneficial mechanism.
The Søberg Study: Design and Protocol
Population: Male winter swimmers, already adapted (2–3 prior seasons), matched with sedentary controls on BMI and diet.
Protocol per session:
- 3 rounds of cold water immersion (1–2 minutes each)
- 2 sauna sessions (~10–15 minutes at ~80°C)
- Alternating cold → sauna → cold → sauna → cold
- Always ending on cold
Frequency: 2–3 sessions per week
Water temperature: Outdoor seawater, seasonally cold (exact temperatures varied)
Primary outcome measured: Brown fat activation via PET-CT scanning
Key finding: This protocol — representing a minimum effective dose — was sufficient to increase brown fat activity, improve glucose metabolism, and produce measurable metabolic benefits.
The Søberg Principle: End on Cold
Ending a session on cold (rather than warming up in sauna or hot shower afterward) forces the body to generate its own heat using brown fat thermogenesis. This is the mechanism through which the metabolic benefit is consolidated.
- Getting into a hot shower immediately after cold immersion short-circuits this process
- The body’s autonomous rewarming is itself the training stimulus for the brown fat
Long-Term Health Benefits of Deliberate Cold Exposure
Based on referenced studies and Dr. Søberg’s own research:
- Lower resting blood pressure
- Lower resting heart rate
- Improved insulin sensitivity and glucose regulation
- Reduced inflammation markers
- Increased catecholamine levels (dopamine, norepinephrine) — effects lasting many hours after exposure
- Improved thermal regulation — greater comfort in cold environments without additional clothing
- Mental health: increased serotonin, better mood, increased energy and positive affect post-exposure (questionnaire-based; mechanistic studies needed)
Cold Adaptation and Practical Entry Points
For those new to cold exposure, a progression might look like:
- Sleep in a cooler room (~19°C) — easy entry, documented benefit
- Wear fewer layers outdoors in autumn/winter
- Cold showers — less studied but likely effective for brown fat activation
- Cold immersion (plunge, open water) — most potent stimulus
You do not need extreme durations. One to two minutes of uncomfortable cold is