Playing airsoft at night or under indoor low light conditions can be a great change of pace. You can experience the action of a gun fight with the highs and lows of watching a horror film. To succeed under these conditions, you must practice good noise discipline.
In low light conditions the importance of hearing is increased. Frequent pauses in movement to listen for your opponent and to get a bearing on your team's position will help insure that you and your team do not become a victim of friendly fire.
In addition to frequent listening stops, you yourself must insure that all equipment is secure and does not generate noise as you move. The metal brackets on your airsoft gun sling and the radio loosely attached to your vest will allow the opposite team to pinpoint you as easily as if you were calling out to them. It is best, before you set out, to jump up and down and listen for noises that you can prevent. Higher frequency noises, such as metal on metal, are much more prone to directional location via sound.
In low light conditions it is usually best to slow your movement down and keep your breathing under control. If your breathing is elevated and forceful your ability to hear is greatly diminished, and you will have to sacrifice crucial time to allow for your breathing to fall back to a level that will not impair your hearing.
You may also want to forgo the usual fully enclosed face and head protection in favor of an eye and face only style mask. The impact from an airsoft BB in the ear can be a painful event, but the increased ability to pin point sounds may be worth the slight chance of being hit in a tender spot. Given that being hit in the head, neck, or ear will cause no permanent damage, you must decide if the increased ability to hear and locate sounds is worth the pain risk.
The choice of magazines you use in your airsoft gun, may also lead to problems on the field. Low and mid capacity magazines are advisable, do to their ability to hold each BB in place. Most high capacity magazines utilize a reservoir that allows ammo to rattle around inside the thin metal container. You can usually hear someone carrying a high capacity magazine from far away, especially if the magazine is partially expended. Medium capacity magazines are a better option as some can handle large quantities of ammo, while maintaining the position of each individual BB.
In airsoft, as well as the real world, having good team movement can make all the difference in the world. Having signals for immediate stopping and relaying positions of sounds heard by team members is paramount. It does no good to practice good noise discipline if you can not hear because your team continues to move and make noise.