Summary
The common thread is that the organic progress of the disease results
in damage to a part of the brain ( the Suprachiasmatic Nucleus or
SCN) which controls body clock or circadian rhythms, but by
using bright light (also known as phototherapy) the disruption
to the normal circadian rhythms can be reduced, making it more likely
that the patient will be able to fit in with the normal daily
sleep-wake cycle.
Phototherapy is simply using strong
artificial lights so the patient is in a light environment which is
much brighter than usually found indoors (but still much less than
found outdoors in spring and summer).
The combination of the particular damage
caused by Alzheimer's Disease to the nerve pathways in the brain and
the gradual dulling of the eyes which happens to all people as they
age mean that the usual indoor levels of light are insufficient to
give the signal that it is daytime (which usually starts off the
normal wake-up processes) so the patient's internal body clock is not entrained
to the usual daily pattern. This affects not only the wake up
processes at the beginning of the day but also the rest and sleep
cycle which usually come into force in the evening.
Phototherapy is already widely used
successfully in the UK and overseas by the NHS and private
institutions to treat jetlag, certain sleep pattern disorders and
Seasonal Affective Disorder (winter depression).
return to top
