How lighting impacts sleep: what you’ll learn in this CPD course

Sleep is fundamental to our health, performance, and wellbeing — yet it is increasingly disrupted by our everyday’s actions and the way we design and light our buildings. This CIBSE-approved CPD course explores the science of sleep, our internal body clock, and how integrative lighting design can actively support healthier sleep–wake rhythms.

Photo by Gregory Pappas on unsplash

Understanding sleep: more than just “switching off”

A clear overview of what sleep actually is, breaking it down into its main stages:

Stage 1 – Drowsy sleep (5–10 minutes):The transition between wakefulness and sleep. Muscle relaxation begins, eyes roll slowly, and we remain sensitive to surrounding noise.

Stage 2 – Light sleep (10–25 minutes):Brain activity and heart rate slow, body temperature drops, and we can still be woken easily.

Stage 3 – Deep sleep (20–40 minutes):The most restorative phase of sleep. We become largely insensitive to noise, slow brain waves dominate, and the body focuses on physical recovery, tissue repair, and growth hormone release.

REM sleep – Paradoxical sleep (20–40 minutes):Characterised by rapid eye movements, vivid dreaming, and muscle relaxation. This stage plays a critical role in memory consolidation and emotional processing.

Understanding these stages, how they are organised in stages and their connections helps explain why both sleep quantity and quality are vital for health.

Our internal clock and the role of light

A key part of the course focuses on the body’s internal clock, or circadian rhythm. This clock is primarily synchronised by the external 24-hour light–dark cycle, known as a photic zeitgeber.

Daylight entering the eyes sends signals to the brain’s master clock — the suprachiasmatic nucleus (SCN) — which regulates bodily functions and hormone production throughout the day. In addition, non-photic zeitgebers such as sleep routines, physical activity, social interaction, and meal timing also influence our rhythms via peripheral oscillators.

Why indoor lighting often works against us

Modern indoor environments frequently provide lighting that is too dim during the day and too bright in the evening. This mismatch can undermine circadian entrainment, disrupt sleep quality, and negatively affect health and alertness.

The course introduces melanopic equivalent daylight illuminance (m-EDI lux) — a metric that quantifies how light affects the melanopsin system in the eye, which is crucial for circadian regulation.

What “good light” looks like

Based on current research, the course outlines practical m-EDI* targets:

Daytime:

Minimum 250 m-EDI lux (vertical) to support alertness and circadian entrainment

Evening (starting at least three hours before bedtime):

Maximum 10 m-EDI lux (vertical) to allow the body to prepare for sleep

Sleep environment:

As dark as possible, with a maximum of 1 m-EDI lux (vertical)

*The m-EDI lux unit is defined in CPD course.

Integrative lighting design in practice

The CPD course introduces Integrative Lighting Design, which considers both:

• Visual needs (seeing and task performance)

• Non-visual effects (circadian regulation, sleep, and wellbeing)

Through a structured design process and a real-world case study, the course demonstrates how lighting solutions can successfully support both visual comfort and biological needs.

Key takeaways

By the end of the course, participants will understand that:

• Sleep is crucial for long-term health and wellbeing

• Light does far more than enable vision — it regulates our internal clock

• Poor indoor lighting can disrupt sleep and circadian rhythms, and affect our health

• Integrative lighting design can support both visual and circadian needs

• Well-designed projects show this approach is achievable in practice

This CPD provides valuable insight for anyone involved in building design, lighting, or occupant wellbeing — offering practical knowledge to help create healthier indoor environments through better lighting.

Follow the CPD course and get your certificate!