
The most common reason magnesium 'fails' is that people expect the wrong thing from it. This sets the expectation properly.
What magnesium is not
It is not a sedative. It will not make you drowsy within twenty minutes. If you are waiting to feel a pull toward sleep, you will conclude it does nothing.
It is not fast. Effects build over weeks as tissue stores replete, not overnight.
It is not a treatment for insomnia as a clinical condition. It is a mineral whose adequacy supports normal sleep physiology.
What it realistically does
Where magnesium helps, the reported changes are usually:
Falling asleep somewhat more easily, though modestly
Less night-time restlessness and fewer leg cramps
A subjective sense of being calmer at bedtime
Better sleep efficiency — less time awake in bed relative to time asleep
Improvement most pronounced in people who were low to begin with
Those are worthwhile. They are not dramatic, and studies reporting them describe moderate effects rather than transformation.

Week 1 — likely nothing noticeable. Possibly mild digestive adjustment depending on form.
Week 2 — some people report falling asleep more easily. Many report nothing yet.
Week 3 — reduced restlessness and cramping are commonly reported around here.
Week 4 — if magnesium is going to help you, it generally has by now.
Judging it at day three is the single most common mistake. Give it a month at an adequate elemental dose in a well-absorbed form.

Be honest with yourself about which of these describes you:
You lie awake with racing thoughts or worry — this is anxiety-driven, and magnesium is not the answer
You snore loudly, wake gasping, or feel exhausted despite eight hours — this may be sleep apnoea, which is common in India and badly under-diagnosed
You fall asleep fine but wake at 3am reliably — different mechanism, and worth investigating
Pain wakes you
Your schedule is chaotic and your bedtime moves by hours — that is a circadian problem, not a mineral one
You drink alcohol most evenings — it fragments the second half of the night regardless of what else you take
In every one of these cases, magnesium may still be worth taking for general adequacy. It will not solve the problem.

A consistent wake time, which anchors the clock
Morning light exposure, which does more than most supplements
Reduced evening light and screens
Melatonin if the issue is timing rather than restlessness — different mechanism, no conflict
A cool, dark, quiet bedroom
Magnesium works best as one part of a routine, not as the routine.

If you have had difficulty sleeping most nights for three months or more, that meets the usual threshold for chronic insomnia and warrants proper assessment.
Ask your doctor about cognitive behavioural therapy for insomnia. It has stronger evidence than any supplement or medication for chronic insomnia, its benefits persist after treatment ends, and it is significantly under-used in India.
Continuing to cycle through supplements for a year is time not spent on the thing that works.
This article is for general information and is not medical advice. Consult a qualified doctor about persistent insomnia.