Humans instinctually hold their breath during tense situations. This is probably an evolutionary holdover from back when we had to hide from predators, as holding one's breath reduces the amount of noise a person makes, possibly keeping them alive if a predator is nearby. This makes the act of taking a breath all the more rewarding when the predator finally leaves. Even now, when hiding from predators is no longer a regular occurrence for people, we still inhale and exhale deeply in response to stress relief.
Whether it be a bomb ticking, a pending execution of an innocent party, a plane doing a nose-dive or one of other countless many situations of a tense or suspenseful nature, characters shown experiencing the nail-biting, breath-holding uncertainty of pending doom will inevitably breathe heavily when the situation relaxes.
- Alice in Wonderland: Exploited by the Queen of Hearts during her croquet match with Alice. Despite blatantly cheating, she still fans herself and sighs as if relieved to have made such a difficult shot.
- Inside Out: A far more relaxed, Tear Jerker example. At the climax of the film, after Sadness is given the chance to let Riley pour her heart out to her parents, she hands control back to Joy. When this happens, Riley smiles as she sighs, having let go of the pain of moving.
- Batman Begins: The people monitoring the water mains get to do this after the pressure finally settles.
- The Matrix. The protagonists must shut down the ship's power and hide from the Sentinels. The Sentinels appear, search around for a while, and leave. After they do, everyone breathes a sigh of relief.
- In Return of the King, immediately after the Battle of Pelennor Fields, the Dead Men of Dunharrow insist that Aragorn hold their oath fulfilled; despite Gimli's suggestion that he hold onto them, Aragorn grants their request. The King of the Dead lets out a sigh and gets this really relieved look on his face as he and the rest of the Dead Men all fade into the wind, as if he's saying, "Oh, that feels soo good."
- Castle: At the climax of a two-parter episode involving a domestic terrorist plot to set off a dirty bomb in the city. Castle and Beckett find the bomb, but with only mere seconds left on the clock. After seemingly resigning themselves to their fate, Castle goes ahead and rips all the wires out, preventing the explosion. Once the shock wears off, Beckett starts gasping with relief.
- Firefly: Wash and Mal share in some heavy breathing after the Reavers don't attack them.
- The Newsroom: Invoked during the episode Fix You; the crew is waiting on confirmation that Gabby Giffords has been killed. When they get the news that she is in fact still alive and awaiting surgery, the technical director tells the graphics guy to "breathe normally."
- Person of Interest:
- Held captive and under torture, Fusco can do nothing but sob and offer vain comfort while his son is about to be executed over the phone. Once the gunshot is revealed to be Shaw who arrived in time to save the kid, Fusco has a sighing fit.
- Taken to the next level in the follow-up scene, where Fusco escapes his restraints and overpowers his captor before strangling him to death. This is followed by another sighing fit.
- Harold has been known to do this often, usually when he's unsure if his friends are alive.
- Crash Bandicoot (1996): Sometimes Crash will let out a sigh when he steps on the level's "finish pad" before he's teleported out of it.
- Crystal Quest: When the player completes a stage by passing through the exit gate, older versions of the game play a sighing sound, obviously meant to represent the player's relief. However, the female voice and inflection used made it sound like something else.
- In Mass Effect 2, after making the hyperspace jump through the Omega 4 relay, the Normandy ends up smack in the middle of a giant space debris field left behind by all the ships that attempted to use it before. After some tense maneuvers, Joker, your resident Ace Pilot, finally lets out the breath he has been holding for a minute and utters only "Too close".
- At one point in Chris Stuckmann's review of Nine Lives (2016), after going on an uncharacteristic rant about how much he hates the film after talking about how the cat owners in the film put a cat's litter box right next to its food, he exhales sharply before quietly saying, "I'm actually physically sweating, I'm-I'm physically sweating."
- Voltron: Legendary Defender:
- Low risk example: After being banned from the Garrison for espionage, Katie Holt infiltrates it as a male student named Pidge Gundarsson. For fear of being recognised by the headmaster, she covers her face with her left hand as he walks past; he assumes she is saluting, says she is using the wrong arm, but continues walking. After he is far enough away, she lets out a sigh.
- Happens again, this time during Allura and Shiro's infiltration of a Galra ship; Allura fumbles through allaying the suspicions of a Galra officer, and sighs heavily after seemingly convincing him all is well.
- In The Little Rascals episode "Science Fair and Foul", Darla does one from behind a stack of crates, after Buckwheat fails to discern that his voice-activated robot was damaged and is now being operated from inside by Spanky and Alfalfa.
- Immediately after the original moon landing, mission control actually said this to the Apollo 11 crew: "...you got a bunch of guys about to turn blue. We're breathing again. Thanks a lot."