Edit in JSFiddle

<h1>Lorem ipsum dolor</h1>
<h2>Lorem ipsum dolor</h2>
<h3>Lorem ipsum dolor</h3>
<h4>Lorem ipsum dolor</h4>
<h5>Lorem ipsum dolor</h5>
<h6>Lorem ipsum dolor</h6>

<div>
    <h1>Lorem ipsum dolor</h1>
    <h2>Lorem ipsum dolor</h2>
    <h3>Lorem ipsum dolor</h3>
    <h4>Lorem ipsum dolor</h4>
    <h5>Lorem ipsum dolor</h5>
    <h6>Lorem ipsum dolor</h6>
</div>

<div class="sweet">
    <h1>Lorem ipsum dolor</h1>
    <h2>Lorem ipsum dolor</h2>
    <h3>Lorem ipsum dolor</h3>
    <h4>Lorem ipsum dolor</h4>
    <h5>Lorem ipsum dolor</h5>
    <h6>Lorem ipsum dolor</h6>
</div>

@mixin headings($from: 1, $to: 6){
    @for $i from $from through $to{
      h#{$i}{
        @content
      }
    }
}

@include headings(){
    font-family:sans-serif;
}

div{
    @include headings(){
      color:red;
    }
}

.sweet{
    @include headings(1,3){
      color:red;
    }
    // headings(4,6) or just headings(4)
    @include headings(4){
      color:blue;
    }    
}