void  StartScreenShake(float afAmount, float afTime, float afFadeInTime,float afFadeOutTime);
 
 
// Insanity
void  SetInsanitySetEnabled(string& asSet, bool abX);
void  StartRandomInsanityEvent();
bool  InsanityEventIsActive();
// Effect
void  FadeIn(float afTime);
void  FadeOut(float afTime);
void  FadeImageTrailTo(float afAmount, float afSpeed);
void  FadeSepiaColorTo(float afAmount, float afSpeed);
void  FadeRadialBlurTo(float afSize, float afSpeed);
void  SetRadialBlurStartDist(float afStartDist);
For breathing, Amnesia uses timers.
A good map for reference is the Cellar Archives, take a look at that.
void TimerPlayerReact(string &in asTimer)
{
    if(asTimer == "scare"){
        PlayGuiSound("react_scare", 1.0f);
        SetRadialBlurStartDist(0.3f);
        FadeRadialBlurTo(0.1f, 0.05f);
        StartScreenShake(0.02f, 0.5f, 1.0f, 2.0f);
    }
    else if(asTimer == "breath"){
        PlayGuiSound("react_breath", 0.9f);
        FadeRadialBlurTo(0.0f, 0.02f);
    }
    else if(asTimer == "breathl"){
        PlayGuiSound("react_breath", 0.5f);
    }
}