var colors = Highcharts.getOptions().colors;

Highcharts.chart('container', {
    title: {
        text: 'Zones on X axis'
    },
    subtitle: {
        text: 'Colors signify periods of increase and decrease'
    },
    xAxis: {
        type: 'datetime'
    },
    series: [{
        type: 'areaspline',
        data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4],
        pointStart: Date.UTC(2015, 0),
        pointIntervalUnit: 'month',
        zoneAxis: 'x',
        zones: [{
            value: Date.UTC(2015, 5),
            color: colors[2]
        }, {
            value: Date.UTC(2015, 6),
            color: colors[5]
        }, {
            value: Date.UTC(2015, 8),
            color: colors[2]
        }, {
            color: colors[5]
        }]
    }]
});