```typescript
export function mergeIntervals(intervals: number[][]): number[][] {
  if (intervals.length === 0) return [];

  // Sort intervals by start time
  intervals.sort((a, b) => a[0] - b[0]);

  const mergedIntervals: number[][] = [intervals[0]];

  for (let i = 1; i < intervals.length; i++) {
    const last = mergedIntervals[mergedIntervals.length - 1];

    if (last[1] >= intervals[i][0]) {
      // Merge if there's an overlap
      last[1] = Math.max(last[1], intervals[i][1]);
    } else {
      // Otherwise, add the separate interval
      mergedIntervals.push(intervals[i]);
    }
  }

  return mergedIntervals;
}
```