When should I start the dim-light window each evening?

Start 2–3 hours before your habitual bedtime — or from sunset or the start of dinner, whichever comes first. If you go to bed at 11 pm, begin dimming lights and filtering screens around 8–9 pm. The goal is to remove blue-wavelength light before your brain expects to start releasing melatonin. The exact timing matters less than consistency — a regular nightly window trains your circadian clock more effectively than an occasional attempt. People with delayed sleep-wake phase disorder may benefit from starting earlier, paired with morning bright-light exposure.

Do blue-light glasses from the chemist actually work?

Most over-the-counter blue-light glasses with a faint yellowish tint — marketed for computer use — block only 5–20% of blue-wavelength light and have no meaningful circadian effect. A 2023 Cochrane review of 17 randomised controlled trials found no significant benefit on sleep quality or eye strain from these lenses. The glasses that do work for circadian purposes have a visibly orange or red-orange tint and block over 90% of light below 530 nm — such as the Uvex SCT-Orange used in published bipolar randomised controlled trials.

Can I use the dim-light protocol if I have bipolar disorder?

Yes — amber-lens glasses blocking over 90% of light below 530 nm have the strongest evidence specifically for bipolar disorder. A 2016 randomised trial found wearing amber lenses from 6 pm to 8 am during acute mania significantly reduced manic symptoms versus placebo by day 7. A 2020 trial confirmed benefit for sleep and circadian rhythm. During depressive episodes the protocol should be used cautiously — extended darkness can deepen depression in some patients. Discuss with your psychiatrist or GP before starting if you have bipolar II or a current depressive episode.

Will the protocol interfere with my ability to drive home in the evening?

Amber lenses are not for driving — they distort colour perception, which creates a safety risk with traffic lights and brake lights. If you wear amber glasses at home in the evening, remove them before driving. Screen filters (Night Shift, Night Light, f.lux) and warm household bulbs are completely safe to use before driving. For the period at home after your last drive, begin your dim-light routine once you are settled indoors and will not be driving again that night.

How does the dim-light protocol help adolescents with late bedtimes?

Adolescents are more sensitive to evening blue light than adults — their clear crystalline lenses transmit more blue wavelengths, and circadian clocks naturally shift later during puberty. Evening blue-light exposure delays melatonin onset and pushes sleep time even later. A family screen-curfew routine, warm bedroom lighting, and limiting overhead lighting after dinner can advance sleep timing by 30–60 minutes over 2–4 weeks. This aligns with the Australian 24-hour movement guidelines, which limit recreational screen time to under 2 hours per day for ages 5–17.

Circadian rhythm sleep-wake disorder and insomnia

Evening dim-light and blue-block protocol: GP guide

By Dr HB Lo, FACRRM Reviewed 26 October 2026 9 min read

The evening dim-light protocol dims ambient lighting to under 50 lux and filters blue-wavelength light in the 2–3 hours before bed, preparing the environment so the body can release melatonin on its natural schedule.

Amber-lens glasses blocking light below 530 nm have the strongest evidence for bipolar mania and delayed sleep-wake phase disorder. Warm bulbs (under 2700 K), screen filters, and a screen curfew in the final hour all contribute.

Combine with CBT-I for chronic insomnia and morning bright-light exposure for phase-delayed patients. Counsel patients that standard pale-tinted blue-light computer glasses lack circadian effect (Cochrane 2023).

Evening light and the circadian clock

The human brain contains a master clock — the suprachiasmatic nucleus (SCN) — that synchronises sleep-wake timing to the external world primarily through light. Intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina, containing the photopigment melanopsin with peak sensitivity around 480 nm (short-wavelength blue light), transmit the “daytime” signal directly to the SCN. When blue-wavelength light reaches these cells in the evening, melatonin secretion is suppressed and the circadian clock is delayed — pushing sleep onset later.

Modern indoor environments flood the evening with blue-enriched LED lighting at 4000–6500 K colour temperature, and smartphone and tablet screens emit substantial short-wavelength energy at close range. A 2015 PNAS study showed that reading a light-emitting tablet for 4 hours before bed delayed melatonin onset by approximately 1.5 hours, suppressed melatonin area-under-curve by ~55%, and impaired next-morning alertness compared with reading a printed book under a dim lamp.

The evening dim-light protocol is a structured behavioural intervention to remove this melatonin-suppressing input in the 2–3 hours before bedtime. It is not a supplement, a device, or a medication — it is a change to the environment that allows the body to do what it does naturally when darkness falls.

A. Core clinical — the AU general-practice framework

Clinical indications

The evidence base is strongest for specific clinical populations and weakest as a generic “screen detox” intervention:

Bipolar I and II disorder (strongest evidence). Henriksen et al. (Bipolar Disorders, 2016) randomised 24 patients with acute mania to amber lenses (worn 6 pm–8 am) or clear placebo lenses as an adjunct to pharmacotherapy. The amber-lens group showed a 14-point greater fall in the Young Mania Rating Scale by day 7. Esaki et al. (Bipolar Disorders, 2020) confirmed the benefit in a double-blind crossover design. For euthymic bipolar patients, nightly blue-block glasses appear to reduce relapse risk as part of social rhythm therapy.

Delayed sleep-wake phase disorder (DSPD). The protocol — combined with morning bright-light exposure and low-dose melatonin (0.3 mg, off-label) — can advance the circadian phase by 30–90 minutes over 2–4 weeks in clinically confirmed DSPD.

Insomnia (sleep-onset subtype). Burkhart and Phelps (Chronobiol Int, 2009) showed amber lenses shortened sleep-onset latency and improved sleep quality in adults with insomnia. Effect sizes are modest; this is an adjunct to CBT-I, not a standalone treatment.

Adolescent late chronotype and poor sleep hygiene. Adolescent circadian clocks shift naturally later during puberty, and evening screen use compounds this further. The dim-light protocol is appropriate as part of school-sleep hygiene counselling.

Shift-worker post-night-shift day sleep. Wearing amber or dark wrap-around sunglasses during the commute home after a night shift prevents morning light from delaying the post-shift sleep opportunity.

Not effective — digital eye strain. A Cochrane review (Singh et al., 2023) of 17 randomised controlled trials found no significant benefit of blue-filtering lenses on visual acuity, eye strain, or macular health. Counsel patients explicitly that the circadian use case and the eye-strain marketing claim are entirely different, and that cheap pale-yellow computer glasses have no circadian effect.

History and assessment

When considering the evening dim-light protocol, take a structured sleep history:

Sleep onset time, total sleep time, sleep efficiency, daytime impairment
Current lighting environment — bulb colour temperature, overhead vs low-level light, screen habits
Screen use in the 2 hours before bed — type (phone, tablet, TV), duration, content
Chronotype (natural sleep-wake preference) — early bird vs night owl
Bipolar history or current mood disorder
Current medications affecting sleep or circadian rhythm

Workup

No investigations are needed to prescribe the protocol. A 2-week sleep diary before and after is the most useful “investigation” — it captures any change in sleep-onset latency, total sleep time, and mid-sleep time. Actigraphy (wrist accelerometer worn for 2 weeks) objectively quantifies circadian phase change when DSPD is suspected.

B. Evidence and clinical controversies

Blue light versus content arousal

A common clinical question: does the wavelength of evening screen light actually matter, or is it the stimulating content (social media, news, games) driving late sleep?

The honest answer is: both matter, and addressing only one misses half the problem. Wavelength matters for circadian timing — blue light specifically suppresses melatonin and delays the circadian phase via the ipRGC-melanopsin pathway. Content arousal matters for sleep-onset latency on any given night, driving cortical hyperarousal independently of circadian phase. An effective protocol addresses both: filter the spectrum AND set a screen curfew. Telling patients to just “turn on Night Shift” without also stopping stimulating content is incomplete advice.

A 2025 Frontiers in Neurology meta-analysis of actigraphic studies found non-significant improvements in sleep-onset latency with blue-block lenses alone in healthy adults, suggesting that in populations without a clinical indication, the content-arousal effect may dominate.

Standard blue-light glasses

The evidence against routine purchase of pale-yellow “blue-light computer glasses” is clear: the 2023 Cochrane review found no meaningful benefit on any visual outcome. These glasses are a multi-hundred-million dollar industry built on a misunderstanding of the mechanism. Correct patients who present having bought them for sleep benefit.

Wearable sleep trackers and orthosomnia

Patients using Oura, Apple Watch, or Fitbit sleep-stage data to assess their protocol response may develop “orthosomnia” — anxiety about tracker scores that itself worsens sleep. Consumer wearables have poor validity for REM and deep-sleep staging versus polysomnography. Redirect attention to total sleep time, sleep-onset time, and daytime function from a sleep diary rather than proprietary deep-sleep scores.

C. The protocol — step by step

Step 1 — Set the window. Identify the patient’s habitual bedtime. Begin the protocol 2–3 hours before. A practical anchor: “from when you sit down for dinner, or sunset, whichever comes first.”

Step 2 — Dim ambient lighting. Switch overhead cool-white LED ceiling lights to table lamps and floor lamps at or below eye level. Replace bulbs with warm-white options under 2700 K (ideally 1800–2200 K for the hour before bed). Target under 50 lux in the room during the window, and under 10 lux in the final hour. A free lux-meter app on a smartphone gives an approximate reading.

Step 3 — Filter or remove screens. Built-in OS night modes: iOS Night Shift (Settings → Display and Brightness → Night Shift → set to “sunset to sunrise” or custom hours), Android Night Light or Bedtime mode, Windows Night Light, macOS Night Shift. Third-party option: f.lux on desktop, with finer colour-temperature control. For circadian-vulnerable patients (bipolar, DSPD, adolescents): no screens in the final hour before bed. A printed book under a warm reading lamp is the gold standard for pre-sleep activity.

Step 4 — Amber lens glasses (for clinical indications). For bipolar mania prevention, DSPD, or shift work: glasses must block over 90% of light below 530 nm. The Uvex SCT-Orange S0360X (industrial safety glasses, ~AUD 30–40 from Amazon AU or hardware suppliers) were used in the published randomised controlled trials. Somnilight and Spectra479 (Australian-made) are purpose-built alternatives. Standard computer glasses with a pale yellow tint are not equivalent.

Step 5 — Bedroom fully dark. Blackout curtains eliminate street-light and car-light leakage. An eye mask adds redundant protection. Cover LED indicators on electronics with gaffer tape. Phone face-down or use a separate alarm clock.

Step 6 — Maintain consistency. The protocol benefits accumulate through a nightly habit, not occasional use. For bipolar patients, this regularity is a core component of social rhythm therapy.

D. Australian operations

MBS billing

Standard general practice consultations (item 23 / 36 / 44) cover counselling the protocol. A Level B suffices for a brief “prescribe and explain” consult; Level C is appropriate for a full circadian and sleep diary review.

When used as part of bipolar mood management, a Mental Health Care Plan (items 2715 / 2717) enables referral to a clinical psychologist for CBT-I combined with the dim-light protocol.

For chronic insomnia with multi-system impact, the GP Chronic Condition Management Plan (item 965 / review 967) from 1 July 2025 supports allied health referral including sleep psychology.

Telehealth items (91890 / 91891) apply under the 12-month existing-relationship rule.

PBS

Melatonin prolonged-release (Circadin 2 mg) is PBS-listed for chronic insomnia in adults aged 55 and over. For DSPD or bipolar adjunct use, the physiological 0.3 mg dose requires compounding and is funded privately. The Circadin formulation at 2 mg can be split or crushed, but compounding is cleaner.

Australian products

The Sleep Health Foundation provides patient-facing handouts on screens and sleep. Spectra479 is an Australian manufacturer of amber sleep glasses (cutting at 479 nm). The Australasian Sleep Association publishes clinical position statements relevant to circadian rhythm disorders.

The Australian 24-hour movement guidelines for ages 5–17 recommend no more than 2 hours of recreational sedentary screen time per day — the dim-light screen curfew is consistent with this recommendation.

Medico-legal

Per Austroads Assessing Fitness to Drive, amber lenses cause colour-vision distortion and are not appropriate for driving. Counsel patients explicitly: remove amber glasses before any evening driving.

E. Special populations

Children and adolescents. The most physiologically susceptible group. Clear crystalline lenses, larger pupils, and greater ipRGC sensitivity mean adolescents experience more melatonin suppression from the same light exposure than adults. A family-wide screen-curfew habit (device-free dinner, no screens in bedrooms after a set time) is more achievable and effective than individual adolescent willpower. Pre-school children: no screens in the hour before bed; bath, book, and dim warm light is the standard routine.

Older adults (over 65). The yellowed crystalline lens naturally filters 70–80% of blue light by age 70, substantially attenuating the melatonin-suppressive effect. Focus in this group shifts to bedroom darkness, regular wake times, and bright daytime light exposure (often dramatically deficient in housebound or residential care patients). Patients who have had cataract surgery with clear intraocular lenses regain the susceptibility of a younger eye — the protocol becomes relevant again for this group.

Pregnancy. Amber lenses and dim warm lighting are non-pharmacological and preferred over melatonin (which crosses the placenta and lacks Australian safety data) for circadian-related sleep difficulty in pregnancy.

Bipolar disorder during depressive phase. Aggressive evening darkness may deepen depression in some patients. Use a modified approach during depressive phases — screen filter and warm bulbs, but hold off on amber lenses — and coordinate with the treating psychiatrist.

When to escalate

Refer to a sleep medicine specialist or clinical psychologist with CBT-I training if:

Chronic insomnia fails to improve after 4–6 weeks of combined dim-light protocol and sleep hygiene
Obstructive sleep apnoea features are present (snoring, witnessed apnoeas, daytime sleepiness) — home sleep study required
Delayed sleep-wake phase disorder does not respond to combined bright-light morning therapy + dim-light evening protocol + low-dose melatonin
Bipolar mood instability worsens despite the protocol

Refer to psychiatry urgently for any new or escalating bipolar episode, particularly if the dim-light protocol as adjunct to pharmacotherapy is insufficient to stabilise mania.

What this article is and is not

This article is patient-education material produced by an Australian GP to help patients understand the evidence behind the evening dim-light protocol and how to use it. It summarises published research and clinical guidelines.

It is not a substitute for a personal consultation with your GP or a sleep specialist. It does not constitute individualised medical advice. Individuals with bipolar disorder, circadian rhythm disorders, or complex sleep conditions should discuss any new behavioural intervention with their treating clinician before starting.

Sources cited

Frequently asked questions

When should I start the dim-light window each evening?

Start 2–3 hours before your habitual bedtime — or from sunset or the start of dinner, whichever comes first. If you go to bed at 11 pm, begin dimming lights and filtering screens around 8–9 pm. The goal is to remove blue-wavelength light before your brain expects to start releasing melatonin. The exact timing matters less than consistency — a regular nightly window trains your circadian clock more effectively than an occasional attempt. People with delayed sleep-wake phase disorder may benefit from starting earlier, paired with morning bright-light exposure.
Do blue-light glasses from the chemist actually work?

Most over-the-counter blue-light glasses with a faint yellowish tint — marketed for computer use — block only 5–20% of blue-wavelength light and have no meaningful circadian effect. A 2023 Cochrane review of 17 randomised controlled trials found no significant benefit on sleep quality or eye strain from these lenses. The glasses that do work for circadian purposes have a visibly orange or red-orange tint and block over 90% of light below 530 nm — such as the Uvex SCT-Orange used in published bipolar randomised controlled trials.
Can I use the dim-light protocol if I have bipolar disorder?

Yes — amber-lens glasses blocking over 90% of light below 530 nm have the strongest evidence specifically for bipolar disorder. A 2016 randomised trial found wearing amber lenses from 6 pm to 8 am during acute mania significantly reduced manic symptoms versus placebo by day 7. A 2020 trial confirmed benefit for sleep and circadian rhythm. During depressive episodes the protocol should be used cautiously — extended darkness can deepen depression in some patients. Discuss with your psychiatrist or GP before starting if you have bipolar II or a current depressive episode.
Will the protocol interfere with my ability to drive home in the evening?

Amber lenses are not for driving — they distort colour perception, which creates a safety risk with traffic lights and brake lights. If you wear amber glasses at home in the evening, remove them before driving. Screen filters (Night Shift, Night Light, f.lux) and warm household bulbs are completely safe to use before driving. For the period at home after your last drive, begin your dim-light routine once you are settled indoors and will not be driving again that night.
How does the dim-light protocol help adolescents with late bedtimes?

Adolescents are more sensitive to evening blue light than adults — their clear crystalline lenses transmit more blue wavelengths, and circadian clocks naturally shift later during puberty. Evening blue-light exposure delays melatonin onset and pushes sleep time even later. A family screen-curfew routine, warm bedroom lighting, and limiting overhead lighting after dinner can advance sleep timing by 30–60 minutes over 2–4 weeks. This aligns with the Australian 24-hour movement guidelines, which limit recreational screen time to under 2 hours per day for ages 5–17.

Source quality

Sources grouped by evidence tier. AU primary tier first; international where AU is silent or lagging; named-author reconstruction where guidelines have not yet caught up. How tiers work.