Melatonin 1 mg is used both in one-off situations (a flight, a routine disrupted by holidays or night shifts) and in courses — for example, to gradually shift your usual time of falling asleep to an earlier one. In both cases the logic is the same: the supplement gives the body clock an evening signal, helping it to readjust or work more steadily.
With regular use, it is important not to let the supplement replace work on the routine itself. Melatonin works more effectively when it is accompanied by a consistent bedtime, dimmed lights in the evening and less screen time before bed. Take away these conditions and the effect will be weaker.
The 1 mg dose was chosen as a small one — it does not produce a heavy sedative effect and does not suppress the body's own melatonin production the way higher doses may. Nevertheless, if you plan to take the supplement for a long time, it is sensible to take breaks from time to time and assess whether you still need it.
If sleep problems are chronic, are not related to your routine or time zones and do not improve over time, this is a reason to see a specialist rather than increase the dose on your own.