Most sleep advice is a list of tips with no way to tell which ones apply to you. Blackout curtains will not help a person kept awake by a racing mind, and a wind-down routine will not fix a 3am waking caused by two glasses of wine. Falling asleep is a sequence of four things, and almost everyone who sleeps badly has a specific one going wrong.
On this page
The four stages, and finding yours
Sleep does not arrive because you got into bed. Four separate things have to line up, and they happen in order.
What has to happen before you sleep
Work out which one fails for you. That is the whole diagnosis.
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Pressure has to build
Adenosine accumulates the longer you are awake. Caffeine blocks it, naps discharge it, and a short night the previous evening raises it.
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The clock has to agree
Your body clock is set mostly by light. It decides when your body thinks night is, regardless of what time you go to bed.
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The nervous system has to settle
A raised stress response keeps you alert. This is the stage that fails when you are tired but wired.
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Core temperature has to fall
Sleep onset depends on your body shedding heat. A warm room or a hot bedroom blocks the signal.
3
is where most people are stuck
Not because it is the most common physiologically, but because a settled nervous system is the stage modern evenings interfere with most.
How to read this. These are the physiological conditions for sleep onset, not a diagnostic test. If two of them apply to you, that is normal and both are worth addressing.
The value of thinking this way is that it tells you what to ignore. If your problem is stage three, buying blackout curtains will do nothing. If your problem is stage two, no amount of chamomile will move it.
Stage one: caffeine, and the cutoff almost everyone gets wrong
This is the single most actionable finding in sleep research and it is routinely underestimated.
In a randomised, double-blind trial, participants took 400mg of caffeine at bedtime, three hours before bed, or six hours before bed, with objective sleep monitoring at home. All three timings significantly disturbed sleep compared with placebo, including the six-hour one.
Six hours. For an 11pm bedtime, that is nothing after 5pm. Most people who consider themselves careful about caffeine are stopping around 2 or 3pm and assuming they are clear.
Stage two: the clock is set by light, and by your wake time
Your body clock does not care what time you get into bed. It is set primarily by when your eyes see bright light, and secondarily by the regularity of your schedule.
Two things follow from that, and they are the two highest-value habits in this article.
Get outside within an hour of waking. Even an overcast New Zealand morning delivers far more light than any indoor lighting. Ten minutes is enough. This anchors the clock and, roughly fourteen to sixteen hours later, is part of what makes you sleepy at a sensible time.
Fix your wake time before you fix your bedtime. Wake time is the anchor the rest of the system hangs off, and it is the one you can actually control. Bedtime is a consequence. Holding a consistent wake time, including at weekends, does more than any bedtime rule.
The weekend lie-in is worth being honest about. Sleeping until 10am on Sunday shifts your clock later, which is why Sunday night insomnia is so common and so predictable.
Stage three: the settle, and why "tired but wired" happens
This is where most modern sleep problems live. You are physically tired, the room is dark, and your mind will not stop.
The mechanism is not mysterious. Your stress response and your sleep system are opposed: alertness and sleep onset cannot both be active. Anything keeping the stress response elevated into the evening keeps you in the wrong state: a demanding day that never got processed, a phone full of other people's problems, an argument at 9pm.
What helps, in order of how much difference it makes:
- A buffer between the day and bed. Thirty to sixty minutes of something undemanding. The purpose is not relaxation as such, it is giving the day somewhere to end other than in bed.
- The phone out of the bedroom. Not primarily for the blue light, which matters less than people think. For the content. A screen full of news or messages is stage-three input at exactly the wrong time.
- Writing tomorrow down. A large share of racing-mind insomnia is unfinished mental accounting. Putting the list on paper closes the loop.
- Daily movement. Anything counts, and it does not need to be near bedtime. A walk is enough.
Stage four: temperature, the one nobody mentions
Your core body temperature has to drop for sleep to begin. It falls in the evening, reaches its lowest point a few hours before you wake, and rises again as morning approaches. That drop is not a side effect of sleep, it is part of what permits it.
Which makes a warm bedroom one of the more common and least suspected causes of poor sleep. Around 18 degrees is the usual recommendation, and most New Zealand bedrooms in summer are well above it.
It also explains a piece of advice that sounds backwards: a warm shower or bath an hour or two before bed helps you sleep. The warmth brings blood to the skin, and when you get out, the heat sheds rapidly and core temperature drops faster than it otherwise would.
Staying asleep is a different problem
Everything above is about getting to sleep. Waking at 3am and not getting back is a separate question with separate causes, and applying onset advice to it is why a lot of people get nowhere.
The usual culprits, roughly in order of how often they turn out to be the answer:
- Alcohol. It is sedating early and disruptive late. As it clears, sleep fragments and REM is suppressed. A nightcap is the most common reason someone falls asleep quickly and still wakes unrefreshed.
- A warm room. Same mechanism as stage four, showing up in the second half of the night.
- An inconsistent wake time. A clock that has been shifted around does not hold a stable night.
- Sustained stress. Cortisol has a daily rhythm that rises towards morning. Under chronic stress that rise starts earlier and higher, and waking at a similar time most nights is a recognisable signature.
The thing to do when you are awake at 3am
Get up.
After roughly twenty minutes awake, leave the bed. Go somewhere dimly lit, do something undemanding and not on a screen, and go back when you feel sleepy. It feels like the opposite of what you want at 3am, and it is the central technique in the most effective non-drug treatment for insomnia.
The reason is associative. Time spent awake in bed teaches your brain that bed is a place where you lie awake, and that association is self-reinforcing. Protecting the bed for sleep is worth more than any single night of lost rest.
Where supplements sit in this
Sleep ingredients are not interchangeable, and the useful question is which stage each one acts on.
| Ingredient | Where it acts | What the research shows |
|---|---|---|
| Glycine | Stage four, temperature |
Lowers core body temperature by increasing blood flow to the skin, which is one of the physiological conditions for sleep onset. Improved subjective sleep quality in people with insomniac tendencies. |
| Ashwagandha | Stage three, the settle |
A meta-analysis of five randomised trials in 400 people found a significant improvement in overall sleep. Effects were strongest in trials running eight weeks or longer, at doses of 600mg a day or more, and in adults diagnosed with insomnia. Morning alertness improved too. |
| L-theanine | Stage three |
An amino acid from tea leaves, studied for supporting a calm, alert state rather than sedation. It is the reason green tea does not feel like coffee. |
| L-tryptophan | Stage two, the clock |
The raw material your body converts to serotonin and then to its own melatonin. It supports the pathway rather than supplying the hormone. |
| Magnesium | Stages three and four |
Required for muscle relaxation and involved in the stress response. Form matters a great deal for how much you absorb, which we cover in our magnesium guide. Trials in older adults with insomnia are small and the authors graded the evidence low, which is worth knowing before anyone quotes a specific figure at you. |
| Apigenin | Stage three |
The compound in chamomile that binds to receptors involved in calming, which is the reason chamomile has been used at bedtime for centuries. |
How to read this. Research on ingredients, not on any particular product. Doses in trials often differ from doses in supplements, and where that matters most, it is stated in the row.
Why a single ingredient rarely does it
Look back at the four stages and the reason becomes obvious. A person whose problem is a racing mind and a warm bedroom has two things going wrong, at two different stages, and a single-ingredient product addresses one at best.
This is the thinking behind Biosphere Sleep. Ten ingredients at therapeutic doses, chosen so that each stage of the sequence has something acting on it: glycine for temperature, ashwagandha and lemon balm and apigenin for the settle, L-tryptophan feeding the body's own melatonin pathway, magnesium for muscle relaxation.
Biosphere Sleep contains no melatonin.Some approved melatonin medicines are available from pharmacies in New Zealand without a prescription, subject to product and age restrictions. Ask your pharmacist about suitable options.
When it is not a habits problem
Some sleep problems are not solved by anything in this article, and recognising that early saves months.
We have written separately on what actually causes insomnia if the difficulty has become persistent rather than occasional.
Sleep is also the largest single lever on how often you get ill. If that is part of why you are here, it appears in our guide to why you keep getting sick, where the strongest study on the subject is set out.
Frequently asked questions
How late can I have coffee?
Six hours before bed is the evidence-based cutoff, and it surprises most people. In a randomised double-blind trial, 400mg of caffeine taken six hours before bedtime still measurably disturbed sleep compared with placebo. For an 11pm bedtime that means nothing after 5pm. If you drink coffee habitually you may feel unaffected, but the disruption showed up on objective monitoring regardless of how people felt.
Why do I fall asleep fine but wake at 3am?
Falling asleep and staying asleep are different problems with different causes, which is why the same fix rarely solves both. Early-hours waking is more often driven by alcohol, a warm room, an inconsistent wake time, or stress raising cortisol overnight than by anything to do with how you wind down. If you are waking at a similar time most nights, look at what you drank and what your bedroom temperature is before changing your evening routine.
Is it bad to lie in bed awake?
Yes, and this is one of the most useful things to know. Lying awake teaches your brain to associate bed with being awake, which makes the problem self-reinforcing. If you have been awake for roughly twenty minutes, get up, go somewhere dimly lit, do something undemanding, and return when you feel sleepy. It feels counterproductive and it is the core of the most effective non-drug treatment for insomnia.
Does alcohol help you sleep?
It helps you fall asleep and damages the sleep that follows. Alcohol is sedating early in the night, then fragments the second half as it clears, suppressing REM and causing the early-hours waking a lot of people blame on stress. A nightcap is one of the more common reasons someone falls asleep easily and still wakes unrefreshed.
What does glycine do for sleep?
Glycine is an amino acid that appears to work by lowering core body temperature, which is one of the physiological signals that sleep onset depends on. Research reports that oral glycine raises glycine levels in the blood and cerebrospinal fluid, increases blood flow to the skin and lowers core temperature, and that taking it before bed improved subjective sleep quality in people with insomniac tendencies. It is a mechanism worth understanding because it explains why a warm bedroom undermines sleep in the first place.
How long before a sleep supplement should work?
It depends on the ingredient. Glycine acts on the same night through body temperature. Ashwagandha behaves differently: the meta-analysis found its effects were more pronounced in trials running eight weeks or longer, so it is better understood as something that builds. Judging a multi-ingredient formula after two or three nights will not tell you much either way.