Sleep is an environmental output, not a willpower input. The body runs a clock that is set every day by the timing of light — and for many autistic and ADHD people that clock runs late by neurology, not by choice, so “go to bed earlier” cannot work. This module covers light as a timing signal, not as visual comfort: the three highest-leverage Reversible moves that anchor the clock — darken the night, lower the evening dose, catch the morning light — then routes you into the Bedroom Design Guide for the full ladder.
This module is about light as a timing signal, not light as visual comfort. The Visual Environment module covers glare, colour temperature and pattern as a sensory-load problem — how a room feels to look at. This one covers the same photons doing a different job: setting the body clock. A near-24-hour clock in the brain decides when you get sleepy, when you wake, and when you feel alert, and it is re-set every day by when light reaches your eyes. When that timing is wrong, sleep goes wrong downstream — and no amount of trying harder at bedtime fixes a clock that is pointing at the wrong hour.
You will finish with three Reversible moves you can make this week — darken the sleep period, lower the evening light dose, and anchor a morning signal — plus a clear read on which of them your situation needs. The heavier, room-changing moves (automated lighting scenes, recessed blackout, layered bedside design) route to your Bedroom Design Guide, which carries the full tier ladder. The temperature arm of the sleep environment routes to the Thermal & Air Quality module and the noise arm to the Acoustic module; both are named here where they matter, because a bedroom is one room and you meet all of it at once.
There is a published recommendation for how much circadian-weighted light a healthy adult should get and when — bright by day, near-dark before sleep (Brown et al. 2022; WELL v2 Feature L03). Most homes miss it in both directions: too dim by day to anchor the clock, too bright in the evening to let it settle. That baseline was derived in the general population, and delayed sleep phase is markedly over-represented in autistic and ADHD people — so the group this module serves is the group the ordinary baseline serves worst. Sensori's position is to recommend the published targets as they stand rather than invent softer house numbers, and to be honest that the strictest of them is demanding in a real home: it is a direction to move in, not a line you pass or fail.
You were routed here by two specific answers, not by a score. The results chart shows eight sensory domains — visual, auditory, olfactory, tactile, thermal, proprioceptive, vestibular, interoceptive — and circadian is not one of them, so there was no “circadian bar” to see. Instead, this module opens when you tell the quiz that light conditions noticeably affect your energy and sleep, or that noise wakes you at night, or that poor sleep has been a pattern for months — because circadian trouble is a matter of timing, not of a sensitivity threshold, and timing does not score on the same axis as the eight domains. If none of that sounds like you, this module is safe to skip.
Sensori reads sensory processing on Dunn’s four-quadrant model — Sensitivity, Avoiding, Seeking and Low Registration, the four cards below. Where those quadrants don’t resolve to a single lead, the results screen reports one of two composite states instead: Managing (you register strongly and actively compensate — Sensitivity and Avoiding at once) or Variable (three or more quadrants elevated, no dominant pattern). On this channel the quadrants describe your relationship to light specifically — because light is the lever, even though the module’s job is the timing it drives.
You notice and are affected by light other people don’t register — the standby LED across the room, the gap at the edge of the blind, the phone screen at its lowest setting, the streetlight through thin curtains. From the outside you look fussy about the dark; from the inside, small amounts of evening or night light genuinely cost you sleep. The priority is removing light at the source: full blackout for the sleep period, and a real drop in the evening dose rather than one dim lamp among several.
You already manage light actively — you keep the overhead off, you have blackout somewhere, you dim your screens, you may already wear an eye mask. The moves in this module are mostly the structural version of what you are already doing by hand: making the blackout complete rather than approximate, and building the evening light-down into the room so it happens without you managing it every night.
You reach for bright, stimulating light late — the big screen, the bright kitchen, the scroll in bed — because it feels good and wards off the flat, under-stimulated evening. That is exactly the input that pushes the clock later, so the move here is not “go dark and bored” but shift the stimulation earlier and change its spectrum: get the bright, cool light into the daytime where it does real work, and let the evening run warm and low.
You miss light cues others use automatically — the dimming evening that signals wind-down, the bright morning that says the day has started. Without those markers the clock drifts and the days blur. The priority is making the signals unmissable: a strong, deliberate morning light anchor you can’t sleep through, and a clear, staged evening dim so the boundary between day and night is legible rather than flat.
Most people present mixed — evening light-seeking and morning under-registration is a common AuDHD pattern, and it is exactly the pattern the three Section 04 moves are built to serve together. The section addresses hypersensitivity and avoiding as its primary thread; where seeking and low-registration change the emphasis, the cards say so.
If you did not take the quiz, this module is useful if you regularly: lie awake for a long time after getting into bed even when tired; feel most awake and capable late at night and wrecked in the morning; find early starts physically punishing rather than just unwelcome; sleep far later on free days than on scheduled ones; or wake through the night and struggle to get back down. Those are the daily signs of a clock that sits late or drifts, which is what this module addresses.
If your late sleep is persistent and it started young, you may be dealing with delayed sleep phase — a recognised circadian pattern that is over-represented in autistic and ADHD people, and is a difference in the clock rather than a bad habit. This module treats it as a design variable, not a diagnosis: you do not need a label to act on any of it. Section 03 sets out how far Sensori will and won’t go on this, and where a GP comes in.
If your sensory tolerance and sleep shift with a hormonal cycle — across the menstrual cycle, in pregnancy or postpartum, through perimenopause, or on HRT — that is real and it interacts with this channel directly; the luteal phase and the postpartum period in particular can raise light sensitivity, and interact with sleep. Where that is you, read the evening and morning moves as things to lean on harder in the weeks they matter, and raise the cyclical pattern with a GP if it is severe.
Chronic-illness sleep — the hypermobility, POTS and ME/CFS cluster, where pain, temperature instability and autonomic arousal fragment sleep — sits mostly outside this channel; it routes to [SPR-01 §13] and the Thermal module, which carry the mechanism and the environmental supports.
The numbers in this module come from a small, consistent evidence base: the Brown et al. 2022 multi-organisation consensus on indoor light (carried in WELL v2 Feature L03) for the melanopic targets; [SPR-01 §13] and [NDR §7] for the mechanism and the morning-light protocol; and the Lok et al. 2025 pathways review for the delayed-sleep-phase picture. One honest note up front on that last source: it studied autistic and ADHD children and adolescents, and Sensori’s reading across to adults is an extension of the same mechanism, not a finding of the paper.
The body clock is driven by a light pathway separate from the one that forms images. Alongside the rods and cones, the retina carries cells (intrinsically photosensitive retinal ganglion cells, ipRGCs) that contain a pigment, melanopsin, tuned to short-wavelength light around 480 nm. They report how much circadian-weighted light is present, not what you are looking at, and they drive the suprachiasmatic nucleus (SCN) — the master clock — which sets the timing of melatonin release, the morning cortisol rise, body temperature and alertness. Because this channel is weighted differently from vision, the effect of a light source is not predictable from how bright it looks: two lamps at identical brightness can hit the clock very differently.
The clock’s own period is close to but not exactly 24 hours, so it has to be re-anchored every day against an outside signal, and light is the dominant one. Its effect is signed by biological time: light in the first hours of your biological day — after your core-temperature low, which sits near the end of sleep — pulls the clock earlier, while light in the biological evening pushes it later. The switch is set by where your body is in its own cycle, not by the wall clock, which is exactly why a late sleeper who gets bright light at what the clock calls 7 a.m. — but which is still their biological night — can be pushed later rather than earlier.
In autistic and ADHD people the clock more often runs late already, by different routes: autistic delayed phase is associated with altered melatonin timing, ADHD delayed phase primarily with dopamine effects on the clock itself. Both produce a late chronotype that is a neurological state, not a preference. This is why the module leads with light timing rather than sleep hygiene — and why “go to bed earlier” produces lost sleep rather than an earlier clock, because onset cannot be moved by intention while the clock still sits late.
Sensori position. Delayed sleep phase is a design-relevant assessment variable, not a behaviour to be corrected — it decides which family of moves is indicated. Sensori states no numeric rate at which a phase shift builds: the available sources disagree and the library carries nothing able to settle it, so the honest statement is directional — sustained, consistently-timed light moves the clock; a single bright morning does not.
What badly-timed light costs, in practice. You are ready for bed at 11 p.m., but the last thing before lying down is a bright bathroom to brush your teeth. Ninety seconds under a cool ceiling light lands squarely in your biological evening, where the signal is signed “delay” — and it can undo more than the earlier hour of dim lamp-light protected, because the clock cannot discount a bright signal it didn’t ask for. The room felt normal. The clock read it as “stay up.”
That mechanism has a direct structural consequence: circadian design is not one instruction but two opposite ones, and the panel below sets them out before the numbers.
Because the clock responds to melanopic light rather than brightness, the dose can be measured at the eye. Two close metrics express it: mEDI (melanopic equivalent daylight illuminance, from the CIE S 026 standard) and EML (equivalent melanopic lux, used by WELL v2 L03). They are two normalisations of the same weighting and differ by about ten percent (EML ≈ 1.1 × mEDI) — closely related, but not interchangeable without the conversion.
The daytime arm is a floor: at least 250 mEDI at the eye across the daytime hours, with light soon after waking doing much of the anchoring. Meeting it is mostly a question of daylight access, not fittings — a spot near a window usually passes, a deep-plan spot usually falls short, and closing that gap with more electric light in the same place is a matter of cost and glare rather than something a lamp resolves, so moving toward daylight is the practical answer. The night arm is a ceiling, and it is two ceilings: no more than 10 mEDI in the three hours before bed, and no more than 1 mEDI during sleep. The second is far stricter because during sleep there is no task to light for, so any residual source — a standby LED, a blind-edge gap, a 3 a.m. phone check — is pure cost.
Colour temperature is a lever on both arms, not the target of either. At the same brightness, 2,700 K warm-white delivers roughly half the melanopic output of cool-white 5,000–6,500 K and about two-thirds that of neutral 4,000 K, so changing bulbs moves the dose without changing how bright the room looks — which is why it is a cheap, useful lever. But a warm bulb at full output can still break the evening ceiling, and a cool bulb in a dark office can still miss the daytime floor. The dose is the target; the bulb is one way to reach it.
Sensori position. Sensori recommends the published figures as they stand — ≥ 250 mEDI by day, ≤ 10 in the evening, ≤ 1 during sleep — rather than substituting softer numbers, and treats the evening ceiling as a direction of travel for a home reader: it is demanding, most comfortably-lit rooms sit above it, and the honest instruction is that every step down counts, not that you have failed at 30.
What a missing morning anchor costs. It is winter, you work from home, and you don’t go outside until lunch. Your clock has no bright morning signal to hold it in place, so it does what a free-running clock does — drifts a little later each day. Three weeks on, you are falling asleep at 2 a.m. and hating your alarm, and none of your evenings changed. The fix wasn’t discipline; it was twenty minutes of real light within an hour of waking.
The evening half of that story overlaps the visual channel’s spectrum work — the same warm-versus-cool decision, read here for its clock effect rather than its comfort effect.
Short-wavelength (cool-white) light drives the melanopsin pathway hardest and suppresses melatonin most, which is exactly what you want in the daytime work zone and exactly what you don’t want in the evening. A fixed 4,000–6,500 K installation therefore delivers a daytime-strength alerting signal at every hour — congruent when a task needs it, a standing cost in the rest-biased rooms this module targets. Warm colour temperature in the evening is the cheap Reversible way to cut that cost; the Visual Environment module carries the full spectrum picture (rendering, flicker, glare) for the comfort side of the same choice.
Before the numbers, one note on the construct that governs how “delayed sleep phase” is named here.
Delayed sleep phase is a recognised clinical entity, diagnosed by clinicians — and Sensori neither diagnoses it nor assigns it a single prevalence figure. What Sensori uses it for is narrower and defensible: it is the variable that decides which family of environmental moves is indicated. You do not need a diagnosis to act on this module, and this module is not a route to one.
The two sides of the comparison are not the same kind of number, and that asymmetry is itself the finding. For ADHD, the figure in circulation is around three-quarters — a review's summary of a literature, covering children and adults together rather than adults alone. For autism there is no equivalent figure at all; the closest measured study found roughly a third of autistic adults reporting a habitual sleep onset between 1 am and 6 am, which is a self-reported clock time rather than a diagnosis. Studies differ in population, in threshold, and in whether they are measuring a disorder or a chronotype. A single confident number would misrepresent the evidence, which is the error the legacy version of this module made. What is not in dispute is the direction: delayed phase is systematically under-treated in neurodivergent people, precisely because it gets read as poor sleep hygiene — so if you have raised this before and been told to try harder at bedtime, that advice could not have worked.
Scope of practice. Environmental light timing, darkness, temperature and noise are inside Sensori’s authority. Diagnosis is not, and neither is medication or supplement guidance of any kind. Melatonin is out of scope: Sensori states no dose, no timing and no product. It is used clinically as a clock-shifter, in the same functional category as morning light and a fixed wake time — and whether it is appropriate, in what form and at what timing is a question for a GP, which is exactly where this module sends it. Where light-timing changes don’t resolve persistent difficulty over a sustained trial, that is the referral: GP, and onward to sleep medicine.
These are Sensori’s canonical circadian defaults, the same figures used across the design guides and audits. The light targets are the Brown et al. 2022 consensus, adopted as published; the temperature and noise rows are borrowed from the thermal and acoustic channels because the bedroom is one room, and each names its home. Melatonin has no row (it is out of scope, above); pre-sleep cooling has no lead-time row, because the reference layer currently disagrees with itself on the number.
Reading the abbreviations. mEDI (melanopic equivalent daylight illuminance) and EML (equivalent melanopic lux) both measure circadian-weighted light at the eye — the same weighting on two scales that differ ~10%. Plain lux measures brightness as the eye sees it, which is a different quantity. CCT (correlated colour temperature, in kelvin, K) is how warm or cool a white light looks — lower is warmer. dB(A) is a sound level weighted to how the ear responds.
These specifications are Sensori’s canonical defaults across modules, design guides, and B2B audit deliverables. The light rows are held in step with a single source-of-record register, so every Sensori product carries the same melanopic targets; the temperature and noise rows are cross-channel borrows whose home registers are named on the rows above, and each row carries its own underwriting-standard anchor.
A closing word on how firm this evidence is. The melanopic targets are a strong, published consensus recommendation — but a recommendation derived in healthy adults, not a trial in autistic or ADHD people, so the reading across to this audience follows from the shared mechanism and the well-documented delayed-phase and sleep-vulnerability patterns, rather than from dosing trials in the population itself. Where the sources genuinely disagree — the rate a phase shift accumulates, the exact pre-sleep cooling schedule — this module states no number rather than invent one. The design moves hold regardless, because each addresses a distinct failure mode and none depends on the precise calibration of the others.
These are the three highest-leverage circadian moves at the Reversible tier — no fixings, no trades, no permission required, and nothing that costs a renter their bond. They act on the same clock at three points of its cycle: darken the sleep period, lower the evening dose, and anchor the morning signal. Each helps on its own, but they only move the clock when they run together — do just one and you leave most of the drift in place; done together they cover the residential circadian problem at this tier.
What has been left out routes elsewhere. Automated lighting scenes, recessed blackout blinds and layered bedside design are Semi-Permanent and Permanent moves that live in your Bedroom Design Guide. The room’s temperature is the Thermal module’s; its noise is the Acoustic module’s. And if your bedroom faces east with no shading, some early-summer light will beat any Reversible treatment — that is a project constraint for [ARR-01 §6], not a design failure on your part.
Ordered by certainty and effort rather than by the hour of day: blackout first (a one-off install that then works unattended), the evening shift second (setup plus a nightly habit), the morning anchor third (a daily behaviour that pays off over weeks).
Some of the product links in the cards below are affiliate links — Sensori Design earns a small commission at no cost to you. All recommended products are selected on merit against the evidence criteria in this module, not on the commercial relationship.
The sleep-period ceiling is the strictest target on the channel — below 1 mEDI — because in the dark the eye is not neutral. Rod photoreceptors gain roughly ten-thousandfold sensitivity over 20–30 minutes, so residual light that is trivial by day sits well above the dark-adapted threshold and is registered through the night, including on partial waking, where it suppresses melatonin. This is the one move that works entirely unattended once installed, which is why it leads.
The performance variable is the edge, not the fabric. The gap between a curtain and the wall usually passes more light than the cloth, so a true blackout needs two elements together: a wide-hung curtain covering the wall edges, and a recess blind sealing the top gap. Either alone leaves a light path large enough to matter. Prioritise this if you wake before dawn, face east, or can’t settle in dim light; it matters less on a dark aspect with deep eaves.
Melatonin suppression rises steeply from very low light levels and flattens well below room brightness — the curve is almost vertical at the bottom and almost flat at the top. So the first big cut, from a cool overhead to a single dim warm lamp, buys most of the benefit, and because the steep part is at the bottom, each further reduction still counts. The evening ceiling is ≤ 10 mEDI through the three hours before bed; that is demanding in a real home, so read it as a direction of travel, not a pass/fail line.
Colour temperature is the cheap lever. At the same brightness, 2,700 K warm-white delivers roughly half the melanopic output of cool-white 5,000–6,500 K and about two-thirds that of 4,000 K — so warm bulbs move the dose without making the room look dimmer. Prioritise this if you light the evening with a bright overhead or a single cool ceiling fixture; it matters less if you already run low warm lamps.
The clock uses the first bright light of the day as its main daily calibration point — the ipRGC signal reaches the SCN through a dedicated tract, and light delivered soon after waking holds the whole cycle in place. This is the load-bearing move for a late or drifting clock, and it runs regardless of sensory profile. Skip it and the two night-side moves have nothing to anchor against: darkness and a low evening quiet the input, but only the morning signal tells the clock where “morning” is.
It shifts the clock earlier only gradually, over weeks of consistent daily use — a single bright morning does nothing, and Sensori does not put a number on the rate because the honest sources disagree. What you can rely on is the direction and the requirement: sustained, daily, soon after waking. The signal that it is working is feeling sleepy earlier in the evening, not waking more easily.
A room built to both the ≤ 1 mEDI darkness target and the ≤ 30 dB(A) quiet target has had its two automatic waking channels — light and sound — deliberately removed. For a sleeper who under-registers cues, or a delayed-phase sleeper fighting to wake at an alarm their clock is working against, that is a real safety consideration: the ordinary morning light and the ordinary alarm may not land. The answer is not a brighter or louder room, which would undo the sleep environment; it is a redundant channel that does not. A vibrating bed-shaker alarm, or a smart-home light set to ramp on at the fixed wake time behind the blackout, gives you a reliable morning signal without lifting the night-time floor. The Acoustic module carries the redundant-alerting mechanism, and your Bedroom Design Guide holds it as a full card (Make sure a critical alarm still reaches you) with the detail for a blacked-out, sound-treated room.
These three are the Reversible tier. The next layer — automated bulbs that run the evening ramp and the morning anchor for you, recessed blackout with full light-seal returns, and a bedside lighting design that keeps the source out of the sleeping field of view — is Semi-Permanent and Permanent, and it lives in your Bedroom Design Guide, which carries the full ladder for the room. Where the constraint is the building itself — an east aspect, unshaded glazing, a bedroom that daylight reaches when you would rather it didn’t — that is an architectural question for [ARR-01 §6], and worth naming as a project constraint rather than something a curtain was ever going to solve.
Each of these produces a meaningfully different result than either component alone. Worth knowing before you start — because on this channel, half a stack often does nothing.
The three Reversible moves are above. When you are ready for the structural layer, these are the forward-pointers into your Bedroom Design Guide and the architectural reference.
The Bedroom Design Guide carries the full tier ladder for the room — the automated lighting scenes, the recessed blackout, the bedside lighting design, and the thermal and acoustic moves that share the space — with the room-specific implementation this module points toward.
Reading order is module first (channel-level mechanism + Reversible action), then the design guide for the room you spend the most time in (full tier ladder, room-specific implementation).
Evidence basis. The melanopic light targets are the Brown et al. 2022 multi-organisation consensus (≥ 250 mEDI by day, ≤ 10 mEDI evening, ≤ 1 mEDI during sleep), carried in WELL v2 Feature L03 and measured on the CIE S 026 metric; the mechanism and morning-light protocol are drawn from [SPR-01 §13] and [NDR §7], with the delayed-sleep-phase picture from Lok et al. 2025 (Lancet Child & Adolescent Health, a paediatric pathways review — adult application by extension). The framework anchor is PAS 6463:2022 (BSI). Full bibliographic detail lives in the Sensori citation database.
Scope of practice. This is design guidance, not clinical advice — Sensori does not diagnose and does not recommend medication or supplements, melatonin included. Where sleep-onset difficulty persists after these environmental changes have been in place for a sustained trial (allow 4–6 weeks, longer for AuDHD), or where sleep is accompanied by loud snoring, witnessed breathing pauses, unrefreshing sleep despite adequate duration or severe daytime sleepiness, that is a reason to see a GP, with onward referral to sleep medicine. One symptom warrants same-day action rather than an appointment: falling asleep, or fighting to stay awake, while driving or operating machinery is a safety emergency — stop and seek urgent medical advice. Where sleep is bound up with acute distress or thoughts of self-harm, the route is crisis and mental-health support, not sleep medicine; Sensori is not a crisis service. In a workplace or education setting — where a duty-holder such as an employer or education provider exists — personal-scale circadian tools of this kind are among those the duty-holder may be required to make as reasonable adjustments under the DDA 1992 (Cth); the changes this module specifies for your own home (a therapy lamp, a bed-shaker alarm, blackout) carry no such legal standing, because there is no duty-holder. Readers with multiple-domain flagging, severe presentations, or unusual constraints can email hello@sensoridesign.com.au — one-on-one consultancy is an option where the design-guide path leaves the situation unresolved.
This is a Sensori intervention module — a free channel-anchored profile-education + Reversible-tier action surface. See sensoridesign.com.au for the full library, including paid design guides for room-by-room implementation.