Narcosis in Diving: Effects, Warning Signs, and How to Act


Post by Honey

May 15, 2024

Diving is one of the most thrilling activities you can experience in your life. It provides an adrenaline rush and allows you to discover the underwater world and its multitude of fascinating treasures and species. However, it is important to always dive safely, following the instructions of certified professionals to avoid any kind of incident.

In this article, we will discuss narcosis, a problem that can occur during deep dives, and provide some key information to help you avoid it.

What is Nitrogen Narcosis?

Nitrogen narcosis, also known as “nitrogen bubble” or “deep-sea drunkenness,” is a phenomenon that affects divers when they dive to certain depths underwater, generally from around 30 metres or more.

This occurs due to the increased pressure of nitrogen in the body caused by the higher water pressure when diving to a significant depth.


Nitrogen narcosis can cause symptoms similar to intoxication, such as euphoria, disinhibition, confusion, disorientation, changes in the perception of time and space, and decreased motor coordination. These effects can impair a diver’s ability to make quick and correct decisions, potentially increasing the risk of diving accidents.

Why Does It Affect Divers?

Let us explain it in the simplest way. When a diver descends, the water pressure increases, compressing the inhaled gases, including nitrogen, in the lungs.

As you descend further, the water pressure compresses more nitrogen into the blood and body tissues. When nitrogen accumulates in the central nervous system, it can interfere with the normal transmission of nerve signals, leading to the symptoms of nitrogen narcosis.


Nitrogen narcosis is believed to primarily affect neurotransmitter receptors in the brain, resulting in a temporary decrease in cognitive and motor function.

Factors That Can Influence

Multiple factors can trigger the onset of narcosis in diving, making it important to pay attention to each one. Hence, the importance of always diving with the assurance of an experienced diving school and a team of highly qualified professionals.

  • It Tends to Increase with Depth
  • Descending too quickly can increase narcosis due to the rapid absorption of nitrogen in the body.
  • The longer a diver spends at significant depths, the more nitrogen accumulates in the body and, therefore, the higher the risk of narcosis.
  • Fatigue and stress can increase susceptibility to narcosis as they affect the body’s ability to handle the physiological stress of diving.
  • Intense physical exercise before or during the dive can increase gas production in the body, affecting narcosis.
  • Consuming alcohol or drugs before diving can increase the risk of narcosis and reduce the diver’s ability to respond appropriately to symptoms.
  • The need to make decompression stops during ascent can increase narcosis due to the additional time spent at significant depths.
  • Colder waters can increase narcosis due to vasoconstriction, which can raise the partial pressure of nitrogen in the body.
  • Diving at high altitudes can increase narcosis due to the reduction in barometric pressure and the corresponding decrease in the partial pressure of oxygen in the inspired air. This can make divers more susceptible to narcosis even at relatively shallow depths.

Common Symptoms of Narcosis

Since narcosis affects the central nervous system, its most common symptoms are related to its proper functioning:

  • A sense of well-being or happiness without apparent reason
  • Disinhibition
  • Disorientation
  • Confusion
  • Alterations in perception
  • Slow or incoherent speech
  • Decreased motor coordination
  • Blurred vision or difficulty focusing
  • A feeling of “bubbling” in the head or body
  • Apathy

What to Do If You Experience Signs of Narcosis

If you experience any signs of narcosis during the dive, it is crucial to act quickly and accurately, relying on the management of the dive instructor. The steps to take are as follows:

  • Inform your dive buddy about your symptoms so they are aware of the situation and can provide support if necessary.
  • If you experience severe symptoms of narcosis, consider stopping the dive immediately. Ascend slowly to a safer depth where the symptoms may diminish.
  • Breathe deeply and calmly to help eliminate excess carbon dioxide and maintain an adequate oxygen flow to the brain.
  • Check your diving equipment to ensure it is functioning correctly and that there are no issues that could contribute to the symptoms of narcosis.
  • Make a safety stop during the ascent to allow the body to gradually eliminate the accumulated nitrogen in the tissues.
  • Try to stay calm and focus on making informed and controlled decisions while managing the symptoms of narcosis.
  • Continue monitoring your symptoms and well-being during the ascent and after leaving the water. If the symptoms persist or worsen, seek medical attention immediately.

Tips from Expert Divers

Diving is a safe practice as long as basic recommendations are followed. It all starts with solid training and a deep understanding of your own limits. Some tips that expert divers usually practice regarding this topic are:

  • Plan your dives carefully and conservatively. Consider factors such as depth, dive duration, current, and visibility before diving.
  • Limit the depth of your dives to reduce the risk of narcosis. If you experience symptoms of narcosis, ascend to a safer depth immediately.
  • Constantly monitor your own mental and physical state during the dive. Pay attention to any changes in your level of awareness, perception, or cognitive ability.
  • Avoid hyperventilation or rapid and shallow breathing, which can increase the risk of narcosis.
  • Communicate your plans and concerns with your dive buddy before the dive. Establish a system of signals to communicate underwater and maintain visual contact whenever possible.
  • Reflect on your experience after each dive and evaluate any symptoms of narcosis you may have experienced. Learn from your experiences and use that information to improve your future dives.
  • If you have any persistent concerns about nitrogen narcosis or need additional guidance, consult with an experienced dive instructor or a hyperbaric medicine professional.

Have you ever experienced narcosis? If so, how did you resolve it? At DPM Diving, we place special emphasis on the safety of every dive, ensuring that our students, regardless of their level, have an enjoyable and risk-free experience.


Meet the amazing Instructor Honey, originally from Bangkok she moved to the islands to do what she loves most: diving and show you the amazing underwater world of Thailand.

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