Sleep difficulty is common, genuinely unpleasant, and has an established evidence base for treatment. It has also become a substantial commercial category, and the overlap between what sells and what works is partial.
General information rather than advice, and persistent sleep problems are a reason to see a doctor rather than to buy something.
What has the strongest evidence
The intervention with the best support is behavioural rather than a product.
Cognitive behavioural therapy for insomnia is recommended as first-line treatment in clinical guidelines in multiple countries, ahead of medication.
It addresses sleep timing, the association between bed and wakefulness, and the thoughts that maintain the problem.
Trials have found effects comparable to medication in the short term and better maintained afterwards.
It is available through therapists, through structured self-help programmes, and increasingly through digital applications that have been evaluated in trials.
It is also the thing least likely to be marketed, since the deliverable is a programme rather than an object.
The specific components that matter
The parts that people can apply without a programme.
A consistent waking time, which anchors the body clock more effectively than a consistent bedtime.
Getting out of bed when unable to sleep, which breaks the association between bed and frustration and is counterintuitive enough that most people do the opposite.
Restricting time in bed to something close to actual sleep time, which increases sleep pressure and is the component people find hardest.
And light exposure, particularly in the morning, which is the strongest signal to the body clock.
Where products have some support
Being fair, some do.
Blocking light and sound. Blackout and earplugs address real environmental disruption, cost very little, and require no claims to justify them.
Temperature control. Cooler environments are associated with better sleep, and anything that achieves that is doing something real.
Certain medications and supplements have evidence for specific circumstances — melatonin for circadian timing issues and jet lag has reasonable support, and its regulatory status and availability vary considerably by country.
And weighted blankets have some small studies with modest positive findings, though the evidence is thinner than the marketing.
Where the evidence is weak
A larger category.
Most sleep supplements, where the evidence is limited, the studies small, and the effects inconsistent.
Sound and light devices claiming to induce particular brain states, where the mechanisms are asserted rather than demonstrated.
Most tracking devices as an intervention. They measure something, and measurement does not improve sleep and can worsen it.
And the substantial category of products addressing sleep hygiene concerns that were never the actual cause of the problem.
The tracking problem specifically
Worth expanding because it is common and the effect is documented.
Preoccupation with sleep data can itself worsen sleep, a pattern that has been described in the clinical literature.
The mechanism is straightforward. Anxiety about sleep is one of the main things that maintains insomnia, and a nightly score provides a new object for that anxiety.
Consumer devices also estimate sleep stages rather than measuring them, so the score being worried about is an approximation.
Clinicians treating sleep problems frequently advise stopping tracking, which is the opposite of what the market suggests.
Alcohol, which is worth its own note
Because it is widely used as a sleep aid and does the opposite.
It reduces the time taken to fall asleep and disrupts the second half of the night substantially, suppressing certain sleep stages and producing fragmentation.
The subjective experience is of falling asleep easily and sleeping badly, and the causal link is frequently not made.
This is well established and it is one of the more actionable findings in the area.
What I would suggest
Fix the free things first — consistent waking time, morning light, a dark cool room, and getting up when awake.
Address alcohol and caffeine timing before buying anything.
If the problem persists beyond a few weeks, seek the behavioural programme rather than a product, since that is what the guidelines recommend and it is increasingly accessible.
And stop tracking it, which for a substantial number of people is the single most effective change available.
Shift work and the limits of advice
Worth acknowledging because standard advice assumes a conventional schedule.
Anybody working nights or rotating shifts is fighting their circadian system rather than merely their habits, and the general recommendations transfer poorly.
Specific strategies exist — controlled light exposure, planned napping, careful timing of caffeine — and they are genuinely different from ordinary sleep advice.
This is an area where occupational health guidance is considerably more useful than consumer material, and where the difficulty is structural rather than behavioural.
Screens, more precisely
Since the advice is repeated in a stronger form than the evidence supports.
Light does affect the body clock and screens do emit it, and the intensity from a phone at typical viewing distance is low compared with daylight.
Research on blue-light filtering features has produced modest and inconsistent results.
What appears to matter more is what the device is used for. Engaging, stimulating or stressful content delays sleep through arousal rather than through light, which is a behavioural effect rather than an optical one.