As winter settled in across the northern hemisphere, our daylight hours shrank and our evenings stretched out. Naturally, during the winter months we spend more time indoors under artificial lighting — screens glowing, LEDs blazing, rooms lit up long after sunset.

There’s a name for the light we’re exposed to at night: ALAN — Artificial Light At Night. And while it feels innocuous, ALAN can quietly reshape the way your body sleeps, recovers and regulates its internal rhythms.

This isn’t about rejecting modern life or living by candlelight. It’s about understanding how light interacts with your biology at a cellular level — and how a few simple shifts can support deeper sleep, steadier hormones and more resilient metabolic health.

The Master Clock: How the SCN Responds to Light

At the heart of your internal timing system lies a tiny structure in the brain called the suprachiasmatic nucleus (SCN). This master clock sits in the hypothalamus and takes its cues directly from light entering the retina.

Morning light signals the SCN to boost alertness and energy.
Evening darkness tells it to slow down, release melatonin and prepare the body for rest and repair.

When ALAN enters the eyes after sunset — especially blue-enriched light from screens, LEDs or bright overhead bulbs — the SCN receives a conflicting message:

It’s still daytime. Stay awake.

This single signal can delay melatonin, disturb cortisol rhythms and unsettle the entire circadian system.

The Body’s Other Clocks: Keeping Time Beyond the Brain

While the SCN acts as the conductor, every organ in your body keeps its own rhythm. These peripheral clocks — found in the gut, liver, pancreas, muscles, skin and immune cells — sync themselves to the timing set by the SCN.

When the SCN is confused by night-time artificial light, the message it sends downstream becomes inconsistent.
This mismatch between the master clock and peripheral clocks is known as circadian desynchronisation.

And it’s this misalignment that underpins many of the physiological effects of ALAN.

Photo by Nubelson Fernandes on Unsplash‍

How ALAN Affects Your Biology

1. Sleep Becomes Lighter and Less Restorative

Blue-rich light suppresses melatonin — not just the hormone that helps you fall asleep, but a key antioxidant involved in nightly repair.
When melatonin release is delayed, the brain struggles to shift into deep, restorative sleep.

2. Stress Hormones Stay Elevated

Cortisol is designed to fall in the evening.
Bright or cool-toned light keeps it higher than it should be, making it harder to unwind and increasing the tendency toward:

Restlessness
Difficulty switching off
Night-time waking

3. Glucose and Insulin Regulation Become Impaired

Peripheral clocks in metabolic tissues rely on strong day–night signals.
ALAN reduces insulin sensitivity and glucose tolerance, meaning even a single evening of bright light exposure can alter how you process food and regulate metabolic processes.

Over time this influences:

Cravings
Morning energy
Fat storage patterns
Inflammation

4. Mitochondria Lose Their Rhythm

Mitochondria (our cellular powerhouses) expect a shift into repair mode at night.
Misaligned light exposure blunts this transition, increasing oxidative stress and reducing energetic efficiency.

5. Cognitive Performance Suffers

The brain needs darkness to transition into memory consolidation and recovery.
Artificial evening light can leave you feeling “wired but tired”, and the next day may bring:

Slower focus
Reduced resilience to stress
Impaired decision-making

For those managing skin conditions, digestive issues, chronic fatigue or mental health difficulties, this additional circadian stress can compound symptoms.

Photo by Simeon Birkenstock on Unsplash‍

Practical Ways to Reduce ALAN Without Disrupting Your Lifestyle

You don’t need to eliminate light — just shape it more intentionally.

1. Keep Evening Lighting Gentle

Instead of bright overheads, opt for:

Lamps
Warm-toned bulbs (special bulbs can be purchased here)
Salt lamps
Low, cosy lighting

Your goal is a softer environment that allows the brain to recognise “night”.

2. Tame Screen Light

If evening screen use is unavoidable:

Activate warm-tone or “night shift” settings
Wear amber or red-tinted blue-light–reducing glasses (available here)
Keep screen brightness as low as comfortable

These small steps reduce melatonin suppression significantly.

3. Create a Simple “Digital Sunset”

Aim for 60–90 minutes without screens or bright artificial light before bed.
This gives the SCN a clear, uninterrupted cue to begin the sleep cascade.

4. Get Morning Light Exposure

Counterintuitive as it sounds, the best protection against evening SCN disruption is morning light.

Just a few minutes outdoors shortly after waking:

Strengthens your circadian rhythm
Helps regulate cortisol/melatonin
Improves sleep timing
Supports metabolic balance

Even cloudy daylight is powerful.

5. Support Your Metabolic Rhythm Through Nutrition

When circadian alignment is compromised, nourishing, timely eating patterns make a real difference:

Include protein and some healthy fats with evening meals
Consider earlier, lighter dinners where possible
Prioritise magnesium-rich and antioxidant-rich foods
Drinking 300ml of tart cherry juice in the evenings can support melatonin levels

These help stabilise blood sugar and reduce oxidative stress at night.

6. Prioritise Darkness in the Bedroom

A truly dark sleeping environment allows the SCN and peripheral clocks to realign fully:

Use blackout curtains
Cover LEDs on chargers and devices
Consider a soft sleep mask if required

Your circadian system is extremely sensitive to even small amounts of light.

Photo by Stephanie Klepacki on Unsplash‍

Final Thoughts

During winter, when we naturally spend more time indoors and the nights arrive early, our exposure to artificial light grows — often without us realising.
Understanding ALAN isn’t about perfection or restriction. It’s about creating an evening environment that supports your biology rather than working against it.

A few simple lighting changes can help restore the rhythms your body depends on to repair, regulate, and thrive.

Why ALAN Is Not Your Friend: How Artificial Light At Night Can Undermine Your Health