Alzheimer's disease and related syndromes (AD) is a disease affecting memory but also the relationship with the environment and empower people. Patients with AD present in 90% of cases of behavioral disorders and of these behavioral disorders include agitation, apathy but also sleep disorders by circadian rhythm impairment.. No study has shown proven efficacy on the behavior of patients with AD. The main objective of the study was to assess the influence of environmental light nighttime sleep of residents.

Alzheimer's disease and related syndromes (AD) is a disease affecting memory but also the relationship with the environment and empower people. Patients with AD present in 90% of cases of behavioral disorders and of these behavioral disorders include agitation, apathy but also sleep disorders by circadian rhythm impairment. In 2014, the Cochrane published a systematic review of the literature over the last 20 years concerning the use of light therapy in patients with a AD. No study has shown proven efficacy on the behavior of patients with AD. The main objective of the study was to assess the influence of environmental light therapy (from 5 a.m to 10 p.m) on nighttime sleep of residents. Secondary objectives were the study of sleep time on the day, anxiety by the COVI scale and behavioral disorders by the NPI scale.

Inclusion Criteria:

• EHPAD residents at Les Pastoureaux Valenton having moderate to severe MASA
• More than 60 years
• Presenting motor behavioral disorders and / or anxiety and / or restlessness and / or insomnia .
• No underlying acute medical problems including no delirium

Exclusion Criteria:

• Residents refusing to lend to experimentation
• Resident who are not matching with the inclusion criteria
• total acquired or congenital blindness
• bedridden patient ( loss of physical autonomy)
• Entry to the residence less than 15 days before the start of the experiment.