This intervention study will investigate the effect of therapy light rooms on sleep, circadian rhythms, mood, behavioural problems and function in nursing home (NH) patients with dementia.

People with dementia often have fragmented night-time sleep, prolonged night-time awakenings and increased daytime sleep. Behavioural and psychological symptoms of dementia (BPSD) (e.g. agitation, depression) are also common. Noticeably, both sleep problems and BPSD are related to a disturbed circadian rhythm. Light is the most important input to the circadian system, and exposure to sufficient daylight is important for entrainment of the circadian rhythm to the surroundings. Dementia patients living in nursing homes (NH) are less exposed to daylight than dementia patients living at home. Bright light therapy is a promising treatment in these patients as it may improve sleep, BPSD, and independent functioning. However, traditional bright light treatment has not been routinely employed in NH patients or patients with dementia. This may be related to difficulties in achieving adherence to the traditional treatment and thus the benefit of bright light therapy for people with dementia still remains unclear.

DEM.LIGHT uses modern LED (light-emitting diodes) technology that enables light therapy with the least possible interference of the day-to-day life in NHs, as the treatment is not confined to a light source presupposing behavioural compliance. Ceiling-mounted LED-sources can be programmed in terms of timing, light intensity and colour temperature. DEM.LIGHT uses this to provide therapy light rooms with a dynamic light condition that better emulates natural light throughout the day. The study is a cluster-randomized trial evaluating the effect of therapy light rooms on various measures of physical and mental health in NH patients with dementia. Data will be collected at baseline, after 8 and 16 weeks of treatment, and at the end of the intervention period (24 weeks).

Inclusion Criteria:

• 60 years or more of age and in long term care (longer than 4 weeks)
• have dementia in accordance with DSM-V
• have either sleep/circadian rhythm disturbances, BPSD as identified by NPI-NH, or severely reduced ADL function
• provide written informed consent if the participant has capacity, if not, a written proxy informed consent from a legally authorized representative

Exclusion Criteria:

• are blind or may otherwise not benefit from light
• partake in another trial
• have a condition contra-indicated to the intervention
• have an advanced, severe medical disease/disorder and/or expected survival of less than 6 months or other aspects that could interfere with participation
• are psychotic or have a severe mental disorder

Although the placebo effect might not be an issue in those with severe dementia, the treatment may affect staff, creating bias such as the Hawthorne effect. Potential changes in staff routines and behaviours in response to the treatment may affect outcome, making a control condition necessary. In this controlled trial, we will compare patients receiving the intervention (therapy light rooms) with control units receiving placebo light ("standard light"). The researchers will install the same standard light solution (100 lux at eye level, 3000K) in all control units. This represents the placebo light intervention, which at the same time ensures a constant standard light condition in all control units.