Academic journal article Iranian Journal of Public Health

Effect of Daylight on Melatonin and Subjective General Health Factors in Elderly People

Academic journal article Iranian Journal of Public Health

Effect of Daylight on Melatonin and Subjective General Health Factors in Elderly People

Article excerpt


Elderly population has rapidly been growing in many countries. The prevalence of successful ageing declined steeply from age 70-74 to age 80+ (1). Two-third of the world's elderly population lives in developing countries such as Iran (2). Life expectancy is increasing, estimated that two billion people will be 60 yr and older by 2050 worldwide and 26 million in Iran (2-4). Elders are exposed to many risks and disabilities such as Psychiatric disorders and these disabilities are 80% in elderly residents of nursing homes (5).

Disruption in sleep-wake cycles and melatonin level is one of the important physiological changes in the aging process, which may result in mood disorders and sleep disorders such as decreasing sleep, early morning awakening. Increased level of sleepiness in daytime is common in elders, and inability to stay awake for social events in evening hours (6, 7). Brief morning light treatment for sleep-wake disturbances in old memory-impaired individuals is effective (5, 8, 9). Freidman et al. found exposure to phototherapy diminished sleep in old individuals with memory impairments. Improvement in sleep and mood of caregivers is independent of phototherapy (10). Evening light exposure can increase the amplitude of circadian rhythm, maybe is the cause to delay sleep phase in elders (11). Light improves depression especially of seasonal kind, sleep disorders and most physical and mental disorders (12). Elderly general health in nursing houses especially somatic complain subscale, severe depression, and social dysfunction subscale is low (13). General health subscale such as depression may be affected with Light therapy.

Light is available in neutral light outdoors or artificial light forms (14, 15). It may be used as supplementary with antidepressants or alone (in seasonal affective disorders) (16). Light can effect on circadian rhythms through changing in melatonin and circadian rhythms and may have significant effect on sleep-wake cycle (17, 18). It seems exposure to daylight does not have adverse effect (19). We maybe prevent problems caused to elderly persons by taking some measures (12, 20).

The present study was conducted to assess the effect of day light on morning and night melatonin, subjective general health using GHQ questionnaire, sleepiness and alertness on elderly people.


Study design

This before-after clinical trial study was conducted on elderly people who lived in Yase-Sefid and Tolooa nursing houses in Hamadan City, the west of Iran, in 2012. Because limitation of participations we could not use case-control study.

At first, we held meeting in nursing home to describe the objectives and explained how the research would be performed. Then, the eligible subjects voluntarily participated in the study and completed a written informed consent.

The study was approved by Ethics Committee of the Hamadan University of Medical Sciences and was registered by Iranian Registry of Clinical Trials (IRCT201203299014N10).


Nineteen elders aged 60 to 101 yr; (mean 80±11.27) participated, including twelve females and seven males. Subjects didn't have cognitive disorders. To determine cognitive disorders, we used Mini Mental State Examination (MMSE) and medical history (21). MMSE score below 27 excluded from study.

Inclusion criteria were as follow: (a) age of 60 yr and above; (b) not having acute mental or physical illness; (c) not having of ophthalmological problems; and (c) not having addiction to alcohol and/or narcotic substances. Inclusion criteria of participants were considered by psychiatric physician and study of their history. Cognitive disorders were examined by psychologist used MMSE.

Illumination condition

The elder's bedroom had insufficient light especially at evening and night. Light intensity was 100 Lux in the bedrooms and 50 Lux in the halls.

Daily routine

The elders passed in the halls in daytime. …

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