Highcharts: xAxis in datetime format (00:00 - 24:00) and n series with n intervals in datetime format

Question

Highcharts: xAxis in datetime format (00:00 - 24:00) and n series with n intervals in datetime format

I will try to explain better, starting with this image, which should make you better understand what I want to display in the graph. (the data will be taken from the database, but it doesn't matter)

enter image description here

During each day (and this graph represents one day), I would like to see on the diagram all users (at most 5-6) who have done at least one "action". These "actions" have a start time and an end time .

In this case, users are a series. And each series is a list of intervals (times) of all actions taken by the user on that day.

An example of a series of users who performed three actions on that day (yes, the timestamp will be multiplied by 1000)

[["1430362800","1430366400"],["1430391600","1430398800"],["1430424000","1430425800"]]

To view on the x-axis the interval 00:00 - 24:00, I will do

xAxis: {
    type: 'datetime',
    tickInterval: 3600 * 1000
}

Each horizontal line must be user-defined. For this I have to set the maximum and minimum of the y-axis. And for example, if users have 3, I will do something like this (I will only add one axis, and the (y) value of each user should be 1,2,3 ...).

chart.addAxis({
    min: 1,
    max : 3,
    ceiling:1,
    tickInterval: 1,
    labels: {
        formatter: function() {
             if (this.value <= 3){
                  return "";
             }else{
                  return null;
             }
         }
    }
});