What sleep hygiene is — and why on its own it often isn't enough

If you’ve ever typed “how to sleep better” into a search engine, you know the list by heart: no coffee after lunch, no screens before bed, a cool, dark bedroom, the same bedtime every day. This is sleep hygiene — the most widespread sleep advice in the world. And if you already have a few months of insomnia behind you, you probably know the second part of the story too: you’re doing all of it, and you still don’t sleep. You may even feel defeated by that — if not even the “basics” help, then something must be seriously wrong with you.

There isn’t. In this piece we’ll do two things. First we’ll go through the main rules of sleep hygiene — not as a list of commands, but with the mechanisms explained: once you understand why caffeine or light work the way they do, you can adapt the rules to yourself instead of following them blindly. Then we’ll look at what most articles leave unsaid: what research says about sleep hygiene as a stand-alone treatment for chronic insomnia — and why the answer is “not enough”.

Light: the conductor of your internal clock

Our internal clock is set each day by the oldest signal on Earth — light. Special cells in the retina, sensitive above all to the blue part of the spectrum, tell the brain’s clock whether it’s day or night; as dusk falls, the pineal gland begins releasing melatonin, the hormone of darkness, which announces night to the body. Evening light delays that signal: research by Anne-Marie Chang and colleagues (2015) showed that evening reading from a light-emitting screen, compared with a printed book, delayed melatonin release, lengthened sleep onset and left people sleepier in the morning.

The mechanism, then: evening light (especially close up and straight into the eyes) tells the clock “it’s still day”. In practice the dogma of “no screens” matters less than three things: less and dimmer light in the evening, complete darkness at night — and, something often forgotten, as much daylight as possible in the morning. Morning light is the strongest regulator of the clock; half an hour outdoors in the morning does more for your sleep than many an evening ritual.

Caffeine: borrowed wakefulness

From the moment you wake, adenosine accumulates in the brain — the substance that creates sleep pressure (more on this two-part system in my piece on insomnia and the nervous system). Caffeine works by occupying the adenosine receptors: it doesn’t cancel tiredness, it only hides it. What matters is for how long: caffeine’s half-life is around five to six hours, which means that at midnight a quarter of the coffee you drank at noon is still circulating. Research by Christopher Drake and colleagues (2013) showed that even caffeine taken six hours before bed measurably disturbed sleep — although the participants themselves didn’t necessarily notice.

In practice: for sensitive people (and insomnia increases sensitivity) it makes sense to have the last coffee in the early afternoon. And watch out for the trap: the worse you sleep, the more caffeine you need, and more caffeine means worse, shallower sleep — one of those quiet loops that keep insomnia going.

Alcohol: a sedative that steals the second half of your night

A glass in the evening really does help you fall asleep faster — which is why alcohol is the most common form of “self-medication” for insomnia. But a meta-analysis by Irshaad Ebrahim and colleagues (2013) shows the price: alcohol does deepen sleep in the first half of the night, but in the second half it fragments it and suppresses REM sleep — precisely the stage that handles emotional processing. The mechanism: the body metabolises the alcohol during sleep, and when its sedative effect wears off, a rebound into arousal follows — hence waking at three, sweating, a pounding heart. In short: alcohol doesn’t give you sleep, it only lends you sleep onset against the second half of the night.

Temperature, rhythm and the bed: three quiet signals

• Cool. For sleep to come, the core body temperature has to fall by about a degree — which is why sleep doesn’t flow in an overheated room. The recommendation of around 17–19 °C isn’t aesthetics but physiology. An interesting trick from the research: a warm bath or shower an hour or two before bed speeds up falling asleep — because the warmed skin then gives off heat and the core cools faster.
• Rhythm. The internal clock loves predictability, and a constant time of getting up matters more than a constant bedtime. A long lie-in at the weekend shifts the clock much as flying across time zones does — and Sunday night becomes the hardest of the week.
• The bed for sleeping only. The brain learns by association: if you work, watch series and ruminate in bed, the bed stops meaning sleep. This principle is in fact already a step beyond hygiene — it’s really stimulus control, one of the core components of behavioural therapy.

To these rules I’d add a note from practice: hygiene isn’t the same for everyone. One person sleeps soundly after an afternoon coffee, another still feels the morning one; for one an evening film helps switch the head off, another is kept awake by the screen. So take the rules as hypotheses rather than commandments — try each one for a couple of weeks and watch whether anything changes for you. That’s how a general list becomes your own personal hygiene, shorter but genuinely yours. And what matters even more: experimenting out of curiosity is psychologically something entirely different from complying out of fear.

Movement, naps and dinner: the forgotten half of hygiene

Three factors that are often missing from popular lists, yet have clear mechanisms:

• Movement. Physical activity during the day raises sleep pressure (more energy spent means more adenosine), lowers the level of arousal and stabilises the internal clock — meta-analyses show that regular moderate exercise shortens sleep onset and improves sleep quality. The only limitation: a very intense workout just before bed warms and arouses the body, so it’s better moved at least an hour or two before bedtime.
• Naps. Every nap subtracts from the night’s sleep pressure — half an hour of sleep at five in the afternoon means less “sleep hunger” at eleven in the evening. In healthy sleepers a short early nap isn’t a problem; in insomnia it is often the quiet leak through which the night’s sleep drains away. If you do nap, keep it short (10–20 minutes) and early in the afternoon.
• Dinner and fluids. A heavy meal just before bed occupies digestion and raises body temperature — two things that work against falling asleep; but hunger keeps you awake just as much. A moderate meal two to three hours before bed is the golden mean. The same goes for fluids: enough during the day, less just before the night, so that trips to the toilet don’t shape your nights.

Now the uncomfortable truth: hygiene isn’t enough as a therapy

Everything listed above is true and everything listed above makes sense. And yet: when Leah Irish and colleagues (2015) reviewed the research on sleep hygiene, they found there is little evidence for its effectiveness as a stand-alone therapy in clinical insomnia — individual recommendations are supported in healthy sleepers, but as a treatment package hygiene consistently lags behind cognitive behavioural therapy for insomnia. In clinical trials, sleep hygiene often even features as a control condition — that is, as the comparison against which the real therapy shows its strength.

Why? Because in chronic insomnia the main maintaining factors aren’t coffee and screens. They’re elsewhere: in the hyperarousal of a nervous system that stays on standby 24 hours a day, in the fear of insomnia, in the effort to sleep, in lying awake and turning the bed into a battlefield, in catastrophic thoughts about tomorrow. No bedroom temperature removes the alarm in the nervous system — and no curtain darkens the thought “what if I don’t sleep again”. That’s exactly why the guidelines recommend CBT-I as the first choice in chronic insomnia: it targets these maintaining factors, not the circumstances.

A simple test I offer people: good sleepers usually break half the rules of sleep hygiene — they drink coffee after lunch, fall asleep in front of the television, sleep in a warm room — and they sleep. Because their system isn’t in alarm, the circumstances can’t get to them. That doesn’t mean hygiene isn’t important; it means it isn’t where chronic insomnia is decided.

Hygiene as the foundation, not the roof

So how should you understand sleep hygiene? As the foundation of a house: you can’t build without it, but on its own it isn’t yet a home. If you drink coffee at six in the evening and sleep at 25 degrees with a lit screen in your hand, every therapy will be working uphill — so put the hygiene in order. But if it’s in order and the insomnia persists, the solution isn’t even more hygiene. The solution is a floor higher up: in the patterns (when you go to bed, what you do when you wake, how long you spend in bed awake), in the thoughts and the fear, and in the arousal of the nervous system — that is, in the components of CBT-I and, when the body no longer knows how to release tension, in work with the body.

In the therapy room I see this sequence almost as a rule. People come with a sense that they’ve “already tried everything” — and when we take stock, it turns out everything came from the same shelf: teas, magnesium, two new pillows, an app, stricter rules. All from the floor of circumstances, nothing from the floor of one’s relationship with sleep. That isn’t an oversight on their part — it’s the logic of a market that sells things, not processes. But the moment someone first sees that their insomnia isn’t a technical problem of equipment but a state of the system is often the moment when treatment really begins. The relief is twofold: there’s nothing wrong with my discipline — and there is a path that aims at the right target.

When hygiene becomes an obsession: the orthosomnia trap

One last warning, which I see more and more often in my work. Sleep hygiene has its dark side: when the rules turn into a ritual that must be carried out to the letter for the night to “succeed”. The same sequence every evening, measuring the degrees, panic if the ritual is disturbed, an app that grades every night. Researchers coined the term orthosomnia for this excessive preoccupation with perfect sleep — and the irony is complete: the more control and effort there is around sleep, the more arousal there is, and the less sleep. Hygiene, which was meant to protect sleep, starts chasing it away.

If you recognise yourself in this — if your evenings have become a project and the rules a source of anxiety — then your next stop isn’t a new rule but an understanding of the fear standing behind all the rules. I’ve written about how the fear of insomnia becomes its main engine, and how to take it apart, in my piece on the fear of insomnia.

What to do with this piece

You may be wondering why advice about sleep hygiene stubbornly holds first place, then. Partly because it’s simple, tangible and requires no one else — you can read the rules and put them in place tonight. And partly because with mild, passing sleep problems it often really is enough: if your sleep was upset only by a stressful week, too much coffee and a shifted rhythm, an orderly foundation will probably bring it back. So hygiene isn’t bad advice — it’s advice for a different problem. And chronic insomnia is a different problem.

Here’s what I suggest. First: check the foundation — morning light, caffeine until the early afternoon, moderation with alcohol, a cooler and darker bedroom, a constant time of getting up, the bed for sleeping. Put it in order once and then stop measuring; a foundation doesn’t need supervision, only maintenance. Second: if after a few weeks of an orderly foundation you still aren’t sleeping — and especially if this has been going on for months — admit to yourself that your insomnia isn’t a hygiene problem, and find the right tool. For me that realisation was once a turning point: as long as I was tidying up the circumstances, I was overlooking the alarm. If you’d like, you can get in touch and we can look together at which floor of the pyramid things are sticking for you.