Sundowning, the late-day confusion, restlessness, and agitation often seen in dementia can be distressing for both patients and caregivers. As research into medical cannabis expands, some scientists are investigating whether THC and CBD, the main active compounds in cannabis, could help calm evening behavioural symptoms. Early findings are intriguing, but the evidence remains limited, and cannabis is not recommended as a treatment for sundowning by UK health authorities.
What Causes Sundowning?
Sundowning is thought to result from disruption in the body’s circadian rhythm, which regulates sleep–wake cycles. Factors such as fatigue, low lighting, and changes in brain chemistry can increase confusion and irritability as the day ends. According to NHS guidance on dementia, behavioural and environmental strategies, such as maintaining routine, ensuring adequate lighting, and reducing stimulation, are the first-line approach.
How Cannabis Might Help
Cannabis interacts with the endocannabinoid system, which helps regulate mood, sleep, and stress. THC acts on CB1 receptors in the brain, influencing neural circuits linked to agitation and sleep regulation. CBD, meanwhile, interacts indirectly with serotonin and GABA pathways, potentially promoting relaxation and stabilising mood.
A 2024 review in Frontiers in Psychiatry (PubMed 38447959) found that balanced THC: CBD formulations improved sleep and reduced evening agitation in small dementia studies, though data quality was rated as “low to moderate.” Similarly, a Swiss feasibility trial (PMC10244760) reported improved rest–wake patterns with THC–CBD oil in advanced dementia, but larger trials are still needed.
What UK Guidelines Say
According to NICE guidance NG97 on dementia management and NICE NG144 on cannabis-based medicinal products, cannabinoids are not recommended for behavioural or sleep-related symptoms in dementia. The Alzheimer’s Society UK also notes that while cannabis may help reduce agitation in some studies, clinical use for sundowning remains experimental.
Clinical Bottom Line
- THC: CBD oils may improve evening agitation and sleep in small studies, but evidence remains weak.
- CBD may reduce anxiety and improve rest-wake rhythm without strong sedative effects.
- NICE and NHS do not recommend cannabis for sundowning or sleep problems in dementia.
- Behavioural and environmental management remain first-line treatments.
Educational Context: AlleviMed
AlleviMed provides educational information about medical cannabis regulation in the UK, helping the public understand how cannabis-based medicinal products are prescribed under MHRA and Home Office frameworks. It does not promote cannabis for dementia but focuses on public awareness of safe, evidence-based practice.
Takeaway
Cannabis compounds like THC and CBD show early promise for calming agitation and improving sleep in dementia, but sundowning relief remains unproven. According to NHS and NICE guidance, non-drug approaches should remain the cornerstone of care until stronger evidence supports the use of cannabis for evening behavioural symptoms in dementia.
