Have you ever felt the urge?

A question that was raised by one of our scuba divers on a recent trip; “why can I go for hours and hours on dry land and not need a wee, but as soon as I jump in and enjoy a couple of minutes of a lovely dive, then I need to go!” What a brilliant question! We did some research and you’ll be happy to know there is a scientific answer… and it’s not just because you are in a skin tight wetsuit, making it the most awkward thing to get out of!

The human body is full of blood. The volume of blood may increase or decrease with eating, drinking and other factors. The body regulates its amount of blood in a very clever way; when the volume of blood in the body increases, the extra blood flows through the veins to the heart. The heart senses the increased volume of blood and nerve sensors in the heart tell the kidneys to release urine. This removes fluid in circulation and reduces blood volume.

So what does scuba diving have to do with it?

The simple answer: cold water and gravity is what affects Scuba Divers!

1. Cold water immersion diaereses – this is the bodies automatic way to minimize heat loss. When you get into the water the body reacts (called the mammalian reflex) and sends blood to the vital organs so therefore increases the amount of blood in the heart and this starts sending signals to the kidneys to make you wee. (That pesky heart!) Did you know as soon as you put your face in cold water it can drop your heart rate by 10% – 20% (and free divers train to drop it to even 50%). I always wondered why you splash a childs face with cold water to calm them down when having a tantrum… there is actually science behind it!
2. Gravity (or lack of it) – weightlessness or near weightlessness also causes blood to shift towards the body’s core. This fluid shift was first observed in astronauts who had to wee more than normal while in space. If you have perfect neutral buoyancy, it is like you have defeated gravity, therefore the blood collects around the heart and similarly to cold water immersion diaeresis, it tells your kidneys to make you wee.

Are we normal?

So needing to wee when you are diving is NORMAL! It’s your bodies way  of protecting itself. You and I both know we don’t need our body to protect us from scuba diving, but it doesn’t think being under the water for an hour is normal so makes us get out to go for a wee! There is no way around it, I always encourage Scuba Divers to go before they dive to try and reduce the sensation. It is still really important to drink water and remain hydrated (avoid drinks with caffeine as this is a diuretic so will also make you need to wee) as being dehydrated can increase the risk of DCS, give you headaches and increases cramps. But there is no magic formula to make you need to wee less while diving!

From now on you know that it is normal that you need to wee when you dive. Every diver feels it, it’s just your pesky body sending blood to the heart that makes you need to wee.

Dan