CWI may have the potential to modify our body’s stress response to stressors in everyday life. In a study where participants engaged in winter swimming (water 0-2°C, 32-36°F) for twenty seconds or cryotherapy (-110°C, -166°F) for two minutes, three times a week for twelve weeks, the body adapted remarkably. After just four weeks, participants showed significantly lower cortisol levels post-exposure, with levels continuing to drop in the following weeks. This adaptation contrasted with the noradrenaline response, which remained consistent even as the body became accustomed to the cold stress. This reduced cortisol response not only diminished the stress perceived from cold but also potentially enhanced the body’s capacity to manage other stressors more effectively.
Cold Water Hazards and Safety
Warm air doesn’t always mean warm water in lakes, streams or oceans. Fifty five degree water may not sound very cold, but it can be deadly. Plunging into cold water of any temperature becomes dangerous if you aren’t prepared for what the sudden exposure can do to your body and brain. Warm air temperatures can create a false sense of security for boaters and beach goers, so if you are planning to be on or near the water, arrive knowing the conditions and how to protect yourself. Cold water quickly removes heat from the body which could lead to cold water shock within the first minute, loss of muscle control within 10 minutes or hypothermia within 20 to 30 minutes. When your body hits cold water, “cold shock” can cause dramatic changes in breathing, heart rate and blood pressure. The sudden gasp and rapid breathing alone creates a greater risk of drowning even for confident swimmers in calm waters. In rougher open water this danger increases. Unplanned immersion in cold water can be life-threatening for anyone without protection from the temperatures or a lifejacket to help you stay afloat. When Cold Shock and Hypothermia begin to impact your ability to think and act, lifejackets and floatation can create extra time for help to arrive or for you to get out of danger. Even the most experienced cold water surfers, swimmers or boaters know to prepare for the conditions.
+ Facts
- Body heat can be lost 4 times faster in cold water than in cold air.
- Wearing a life jacket significantly increases chances of survival.
- Cold shock can be just as severe and dangerous from water temperatures of 50-60F (10-15C) as it is from water at 35F (2C).
- Gasping for a breath or rapid breathing from sudden immersion can be triggered by water as warm as 77F (25C).
+ Understanding the Danger of Cold Water
Knowing what happens when you enter cold water and what you can do in those first seconds could save your life and give time for help to arrive.
COLD SHOCK
- Gasping for Breath and Rapid Breathing (2-3 Minutes or More)
Cold Water Immersion can trigger involuntary gasping, rapid breathing or hyperventilating due to the “shock” of sudden immersion. This uncontrolled rapid breathing can quickly create a drowning emergency if you inhale water and cannot stay afloat. - Heart and Blood Pressure Problems
Cold water can cause a sudden spike in heart rate and blood pressure. This increase can cause heart failure and stroke for vulnerable people. - Cognitive Impairment
Cold shock can cause an immediate panic, fear or stress reaction that then impairs clear thinking and decision making. Extended exposure and the onset of hypothermia can further hamper cognitive ability and the ability to choose the right actions to avoid severe injury or death.
PHYSICAL INCAPACITATION
Physical incapacitation is a loss of muscular control in the arms, legs, hands and feet, and the impact can be felt within seconds of entering cold water. The longer the exposure, or the colder the water, the more severe the impact can become. With a loss of muscular control to keep your head above the water, along with the lack of a lifejacket or floatation device, drowning will become inevitable. Symptoms may include weakness, exhaustion, and an inability to control fingers, hands, arms or legs. The progressive loss of muscular control makes staying afloat without assistance or self-rescue virtually impossible.
HYPOTHERMIA
The onset of hypothermia begins with a core body temperature to 95F (35C). Beyond the initial dangers of cold shock in the first 1 – 3 minutes of immersion a person’s body temperature will continue to drop increasing the risk of drowning or death. As the core body temperature continues to drop the impairments to physical and cognitive ability also increase until drowning or death without rescue become inevitable.
If you get yourself or help someone else escape from cold water, get into a warm, dry, protected environment as quickly as possible. Even removed from cold water a victim’s core temperature can continue to drop to dangerous levels.
+ Risks
Cold water risks include immersion into any body of cold water: oceans, lakes, rivers, streams or pools. In many places, parts of the year and bodies of water warm air temperatures may not coincide with safer, warm waters. Many areas of the country have warm days and yet the water stays cold. In the Pacific Northwest ocean temperatures may stay in the 60’s. Weather conditions along any large body of water can cause dramatic drops in water temperatures even in the middle of summer. In the waters around Annapolis, MD temperatures may only be above 60F for 5.5 months of the year. Cold Shock and the dangers of sudden cold water immersion can happen along almost any shore at any time of the year. Water activities that put people at risk include kayaking, canoeing, whitewater rafting, paddle boarding, and lake boating.
Risks that may cause immersion in cold water include:
- Turbulent water, waves and surf which can overturn watercraft or fill a boat with water.
- Falling off watercraft, docks, rocks or jetties.
- Falling through the ice.
- Sneaker waves that can pull beach walkers into the surf.
- Rising tides, rising rivers, tidal currents and rip currents.
+ Preparedness
Being prepared for an outing on cold water means being prepared for the possibility of suddenly being immersed into cold water. Your ability to survive cold water immersion depends on your ability to stay afloat and to stay warm until help arrives. Below are several things to consider prior to venturing out on cold water.
- Always wear a life jacket in and around the water.
- Always dress for water temperature, not for air temperature.
- Some examples are:
- Wet suit
- Dry suit
- Immersion suit
- Survival suit
- Exposure coveralls
- Be sure to check the weather and water temperature before you go out on the water
- If water is too cold, consider staying off/out of water until water is warmer
+ Take Action
Cold water can kill. The following guidelines and images from the U.S. Coast Guard will increase your chance for survival:
- Stay calm.
- Minimize time in the water. Get out as soon as possible safely.
- If possible, utilize any floating objects to get out of the water.
- Keep as much of your body out of the water as possible.
- Evaluate your options.
- If you can swim to safety, stay calm and do so.
- If you cannot swim to safety, conserve energy and heat and await rescue.
- If you cannot get to safety, assume the Heat Escape Lessening Position (H.E.L.P.) position. This protects the critical body areas and slows down the loss of heat. H.E.L.P position means:
- Draw your knees to your chin and keep your legs together.
- Press both arms against your side and keep your head out of the water.
- If possible, form a huddle in the water with others to conserve body heat.
H.E.L.P. Huddle position If you need to treat yourself or someone else that has been submerged in cold water, follow the steps below (developed by the Red Cross):
- CALL 911 or the local emergency number.
- Gently move the person to a warm place.
- Monitor breathing and circulation. Give rescue breathing and CPR, if needed.
- Remove any wet clothing and dry the person.
- Warm the person slowly by wrapping in blankets or by putting on dry clothing.
- Hot water bottles and chemical hot packs may be used. Wrap the person in a towel or blanket before applying.
- Do not warm the person too quickly. Do not immerse the person in warm water. Rapid warming may cause dangerous heart arrhythmias.
- Warm the core first (trunk and abdomen), not the extremities (hands, feet). Warming hands and feet first and can cause shock.
+ Resources, Links and Partner Information
- National Center for Cold Water Safety
- Ocean Positive
- National Safe Boating Council
- United States Coast Guard
- Boating Safety Division
- Cold Water Survival
- Hypothermia Prevention: Survival in Cold Water
- Cold Water Safety and Survival
- Cold Water and River Safety
- Cold Water and River Safety – Spanish Version
Jumping into the Ice Bath Trend! Mental Health Benefits of Cold Water Immersion
Have you ever considered how taking a cold plunge might affect your mental state? Beyond the initial shock, CWI is proving to have profound effects on brain health and mental well-being. Initially popular as a recovery technique among athletes, it has now evolved into a bold wellness practice for those seeking to enhance their overall health. This practice, which involves plunging into cold water (roughly 10-15°C, 50-60°F), has ignited significant research interest, and emerging studies now suggest that CWI can improve mood , decrease stress , and potentially slow the progression of neurodegenerative diseases .
“I personally do cold water immersion and find it to be an immensely rejuvenating activity,” says Stanford Psychiatrist, Vanika Chawla, MD, member of the Lifestyle Medicine Cognitive Enhancement pillar.
CWI can take many forms, each involving its own protocol and equipment. The most common forms include:
- Ice Baths: Traditionally utilized by athletes for recovery after intense physical activity, ice baths require submerging the body up to the neck in ice-cold water. Also known as cold plunging, this practice generally lasts only a few minutes and involves limited movement.
- Cold Showers: A more accessible form of CWI, taking cold showers can offer many of the same benefits as ice baths but are easier to incorporate into daily routines.
- Open Water Swimming: This active form of CWI involves swimming in cold rivers, lakes, or oceans, allowing for longer exposure times to the cold.
- Cryotherapy Chambers: Though they do not involve water, cryotherapy chambers expose the body to extremely cold air temperatures for brief periods, stimulating a physiological response similar to that achieved through water immersion.
Choosing the type, temperature, and duration of CWI depends on your cold tolerance and the resources available to you. It is generally recommended to aim for a temperature that feels uncomfortable but still safe (no colder than 10°C, 50°F). If you have any form of access to cold water, whether it be a lake, a river, or your home shower and bathtub, you can participate in CWI and begin to explore its benefits.
Can Cold Water Plunges Improve Mental Health?
While the idea of diving into extremely cold water seems unappealing to most, recent studies have shown that CWI offers emotional benefits. In 2021, researchers recruited undergraduate students to take a 20-minute dip in chilly sea water (13.6°C, 56.5°F) and report their emotions before and after using a Profile of Mood States questionnaire. Compared to controls, the students who engaged in CWI experienced a shift in mood, noting a significant decrease in negative emotions like tension, anger, depression, fatigue, and confusion. Moreover, they experienced boosts in positive emotions such as vigor and self-esteem. Further research involving thirty-three adults new to cold-water swimming highlighted similar benefits. After immersing in a cold bath (20°C, 68°F) for just five minutes, participants reported feeling more active, alert, attentive, proud, and inspired.
These studies, which utilize self-reported questionnaires, indicate that cold-water immersion may significantly enhance mood and overall psychological well-being. It appears to activate traits associated with increased motivation and vitality, while simultaneously diminishing feelings of distress and nervousness.
How to Lower Cortisol Levels Naturally
CWI presents a unique stimulus for the body, prompting significant shifts in its hormonal stress response, particularly involving cortisol, a key regulator of stress. Unlike other stress hormones such as noradrenaline, cortisol levels remain relatively unchanged during the initial shock of cold water. Research highlights an intriguing aspect of cortisol dynamics: while levels do not significantly change during CWI, they significantly decrease afterward.
For example, a study concluded that a one-hour CWI session, whether in thermoneutral (32°C, 90°F), cooler (20°C, 68°F), or cold (14°C, 57°F) water, did not lead to an increase in blood cortisol concentrations. Instead, cortisol levels tended to decrease across all temperatures tested and remained below initial levels an hour after immersion. These findings suggest that cortisol production is not significantly activated by CWI, contrary to what might be expected under typical stress conditions. In fact, CWI may have potent stress-modulating effects. Further research indicates that cortisol levels remain considerably lower for up to three hours after just 15 minutes of CWI (10°C, 50°F). This pattern of response reveals a sophisticated regulatory mechanism, suggesting that CWI can effectively diminish feelings of stress following a session.
CWI may have the potential to modify our body’s stress response to stressors in everyday life. In a study where participants engaged in winter swimming (water 0-2°C, 32-36°F) for twenty seconds or cryotherapy (-110°C, -166°F) for two minutes, three times a week for twelve weeks, the body adapted remarkably. After just four weeks, participants showed significantly lower cortisol levels post-exposure, with levels continuing to drop in the following weeks. This adaptation contrasted with the noradrenaline response, which remained consistent even as the body became accustomed to the cold stress. This reduced cortisol response not only diminished the stress perceived from cold but also potentially enhanced the body’s capacity to manage other stressors more effectively.
The main take away from this study is that by reducing cortisol production in response to repeated cold exposure, participants might also release less cortisol in response to other stressors in everyday life, thus fostering a more resilient physiological state over time.
“Resilience is the ability to adapt to life’s stressors and adversities,” says Dr. Chawla. “The body and mind are interconnected, therefore greater physiological resilience may lead to greater psychological resilience as well.”
How Cold Water Immersion Impacts the Brain
CWI has been scientifically observed to influence brain function, affecting mood, stress response, and potentially brain health through several mechanisms. The immediate physiological response triggered by CWI is largely due to the dramatic change in temperature. A dense concentration of cold receptors in the skin detects this change, leading to a surge of electrical impulses from peripheral nerve endings to the brain. This intense stimulation activates various neural pathways, initiating a cascade of chemical responses designed to help the body manage and adapt to the stressor.
During the initial shock of CWI, the body experiences stress and discomfort due to the sudden drop in temperature. To counteract this, endorphins , the body’s natural pain relievers, are released. These endorphins not only reduce pain but also enhance feelings of well-being, akin to the “runner’s high” that often occurs in other physically demanding or stressful situations.
CWI also activates the sympathetic nervous system (SNS), which controls our “fight-or-flight” responses. This activation leads to a significant increase in noradrenaline (also known as norepinephrine) , an excitatory neurotransmitter that not only helps manage stress but also boosts energy and focus. The surge in noradrenaline increases blood flow to the brain, potentially causing feelings of euphoria.
These two neurotransmitters play complementary roles. While norepinephrine prepares the body to handle acute stress by enhancing alertness and readiness, endorphins work to soothe pain and promote a positive mood. This dual response helps individuals cope with the immediate impacts of cold exposure more comfortably and can make the experience of cold water immersion more tolerable–and potentially even rewarding.
Regarding whether CWI has long-term positive effects on the brain, research indicates inconsistent results with respect to the increase of endorphin levels. It is possible that not everyone experiences this endorphin response to CWI, and among those who do, the effect may diminish over time, as the body becomes accustomed to the cold exposure. On the contrary, the increase in noradrenaline continues with each session of CWI, even after the body has adapted after months of regular practice.
These findings underscore the potential of CWI to be used as a reliable tool for improving energy, focus, and mood. These findings also point to the potential of CWI to be used in the treatment of neurological conditions that involve low noradrenaline, including anxiety and depression. However, more research is needed to understand if CWI has long-term effects on emotional well-being outside the water.
Also, CWI may improve brain function through the release of cold-shock proteins, which are produced by the body in response to cold conditions. Animal studies reveal that proteins like RNA binding protein (RBM3) play a crucial role in repairing and regenerating nerve cell connections after they’ve been exposed to cold. Additionally, studies have demonstrated that over-expressing RBM3 can help prevent neuronal connection loss in mice with neurodegenerative diseases. Although there is limited evidence in humans, these findings in mice suggest that regular CWI could potentially boost the expression of such beneficial proteins in humans, offering protection against or slowing the progression of neurodegenerative diseases by preserving and reinforcing neural connections.
Reaction to Cold Water: Full-Body vs. Facial Immersion
Physiological responses to CWI differ significantly based on whether the exposure is to the full body or just the face. Full-body immersion exposes a significant surface area to cold, inducing thermal stress that can substantially lower skin and core body temperatures. This extensive exposure activates the sympathetic nervous system, which in turn triggers a release of neurotransmitters and hormones that drive the stress response. Consequently, this leads to vasoconstriction, an increased heart rate, and a heightened metabolic rate, all of which help preserve body heat and maintain core temperature.
In contrast, immersing just the face in cold water activates parasympathetic activity , which is responsible for “rest and digest” functions in the body. This effect is likely due to the mammalian diving reflex —an evolutionary adaptation that optimizes respiration and conserves oxygen by preferentially directing oxygen to vital organs. The diving reflex is mediated by the vagus nerve , which activates the parasympathetic system and releases a sense of calm. The trigeminal nerve in the face also plays a crucial role when stimulated by cold, sending signals that further enhance parasympathetic output, decreasing heart rate, and boosting digestive activity.
These differences highlight how CWI can be strategically used to target specific physiological responses and therapeutic outcomes, depending on whether the exposure is localized to the face or involves the entire body.
“I sometimes recommend facial cold water immersion to my patients as part of the T in TIPP skills to help people with emotion regulation. TIPP stands for temperature, intense exercise, progressive muscle relaxation, and paced breathing,” says Dr. Chawla. “These skills involve changing your body chemistry to shift emotions. Some people find brief facial immersion in cold water or taking a cold shower to be helpful in shifting their body chemistry and thereby shifting their emotional state.”
Safety Considerations
CWI can offer several health benefits, but it’s essential to approach this practice with caution due to potential risks. One of the most obvious risks is hypothermia, as immersing in cold water significantly drops body temperature. To prevent hypothermia, limit immersion time to no more than 10 minutes .
Furthermore, it is important to understand the cold shock response. Entering cold water suddenly can trigger an involuntary gasp reflex followed by hyperventilation. Hyperventilation increases the risk of drowning (especially in open water plunging) and can also lead to arrhythmias or even a heart attack, particularly in those with underlying heart issues. To better manage the cold shock response, it’s advised to enter the water slowly, allowing your body to adjust to the temperature gradually.
It is also important to never swim alone regardless of your swimming strength or experience. Having a partner ensures that help is readily available in case of an emergency, such as cramps, sudden illness, or difficulty in the water.
Finally, remember to allow your body to gradually acclimatize to whatever CWI technique you choose. If you are a beginner, begin with shorter durations (2 minutes) in warmer water (roughly 20°C, 68°F), progressively moving to colder temperatures with longer durations as your body adapts.
“This intervention is not for everyone. It’s important for people to consider what works best for their individual needs,” says Chawla. “If you are going to try CWI, be mindful of how it impacts your mind and body and incorporate the activity into your routine accordingly.”
