Understanding Sundowning
The science behind late-afternoon confusion, agitation, and anxiety in dementia, and why it happens when the sun goes down.
What is
Sundowning?
Sundowning is a pattern of behavioural and psychological symptoms that emerge or worsen in the late afternoon and evening hours.
Common Symptoms Include:
Agitation & Restlessness
Pacing, inability to settle
Confusion & Disorientation
Not recognising familiar places or people
Anxiety & Fear
Heightened emotional distress and worry
Aggressive Behavior
Verbal outbursts, physical resistance to care
Sleep Disturbances
Difficulty falling asleep, frequent waking
Wandering & "Going Home"
Wanting to leave, searching for deceased relatives
The Impact on Families
Sundowning affects 66% of people with dementia at some point in their journey. For caregivers, these evening hours become the most challenging part of the day: physically exhausting, emotionally draining, and often leading to caregiver burnout.
It's one of the primary reasons families make the difficult decision to transition their loved ones to expensive institutional care.
Why Does Sundowning Occur?
The answer lies deep within the brain's circadian timing system, our biological clock that regulates when we feel alert and when we feel sleepy.
The Circadian System: Our Internal Clock
At the heart of our sleep-wake cycle is a tiny cluster of neurons in the hypothalamus called the suprachiasmatic nucleus (SCN). This is your body's master clock. The SCN orchestrates a 24-hour rhythm that governs:
- •Hormone production (especially cortisol and melatonin)
- •Body temperature regulation
- •Blood pressure and heart rate
- •Alertness and cognitive function
- •Sleep-wake cycles
The SCN keeps itself synchronised to the external 24-hour day through light entering the eyes. Special photoreceptor cells in the retina detect light and send signals directly to the SCN.
☀️ Morning Light
Blue-rich morning light (470-480nm) signals to the SCN that it's time to wake up. This suppresses melatonin production, raises cortisol, and increases alertness.
🌙 Evening Darkness
As light fades, the SCN triggers the pineal gland to produce melatonin, the "sleep hormone", helping us wind down and prepare for rest.
What Goes Wrong in Dementia?
SCN Degeneration
In Alzheimer's disease and other dementias, the SCN itself degenerates. Post-mortem studies show significant cell loss and reduced neuropeptide production in the SCN of people with dementia. The master clock literally breaks down.
Reduced Light Sensitivity
Dementia damages the retinal pathways that communicate light information to the brain. Even when exposed to bright light, the SCN may not receive or process the signal properly. It's like the clock is running, but can't see what time it really is.
Melatonin Dysregulation
The normal evening rise in melatonin becomes disrupted. Some people with dementia produce melatonin at the wrong times, or in insufficient amounts. The hormone that should say 'time to sleep' goes missing.
Insufficient Light Exposure
People with dementia often spend less time outdoors and in bright light environments. This compounds the problem—the already-damaged circadian system receives even weaker signals, further desynchronizing from the 24-hour day.
The Cascade: From Broken Clock to Sundowning
When the circadian system loses its rhythm, a cascade of physiological and psychological changes unfolds, particularly in the late afternoon and evening:
Cortisol Confusion
Cortisol normally peaks in the morning and declines by evening. With circadian disruption, cortisol rhythms flatten or invert, leaving the person either too alert when they should be winding down, or experiencing stress-like arousal at the wrong times.
Cognitive Fatigue Accumulates
Throughout the day, mental fatigue builds up. By late afternoon, cognitive reserves are depleted. For someone with dementia, already struggling with impaired brain function, this exhaustion becomes overwhelming, manifesting as confusion and agitation.
Shadow and Light Changes Trigger Disorientation
As daylight fades and shadows lengthen, the visual environment changes dramatically. For someone with dementia and perceptual deficits, these changes can be frightening and disorienting when a familiar room suddenly looks unfamiliar.
Sleep-Wake Boundary Blurs
Without clear circadian signals, the brain can't distinguish between 'awake time' and 'sleep time.' This creates a twilight state, neither fully alert nor properly sleepy, that is deeply uncomfortable and anxiety-provoking.
The result: A perfect storm of biological confusion, cognitive overload, perceptual distortion, and hormonal chaos: all converging in the late afternoon and evening. This is sundowning.
The Science of Light Intervention
If the problem is a broken circadian clock, the solution is to reset it using the same signal that synchronizes healthy brains — light.
💙 Blue Light (Morning Signal)
This wavelength most strongly activates the photoreceptors that communicate with the SCN. Exposure to blue light in the morning and afternoon helps anchor the circadian rhythm, suppresses mistimed melatonin, and increases alertness.
❤️ Red Light (Calming Support)
Red light at 630nm doesn't disrupt evening melatonin production but supports cellular function and has been shown to have neuroprotective effects. It helps create a calming environment without interfering with the sleep-wake cycle.
Clinical studies have demonstrated that properly timed bright light therapy can:
✓Reduce agitation and behavioral symptoms by up to 89%
✓Improve nighttime sleep duration by an average of 2.5 hours
✓Decrease caregiver burden and improve quality of life
✓Extend time living at home before institutional care is needed
Introducing Harmoni
We've taken decades of chronobiology research and created a device designed specifically for people living with dementia.
Learn More About Harmoni