The effect of night lighting on sleep

Nazarbayeva A. S., Amansheyeva A. B.

Department of general hygiene and ecology
Scientific supervisor- c.m.s., associate professor G. A. Berdesheva
West Kazakhstan state medical university named after Marat Ospanov
Aktobe city, Republic of Kazakhstan

Key words: healthy sleep, biorhythm, melatonin, pineal gland, sleep disturbance, night

lighting, questionnaire HAM

Relevance.Sleep was long considered just a block of time when human brain and body shut down. Thanks to sleep research studies done over the past several decades, it is now known that sleep has distinct stages that cycle throughout the night in predictable patterns. How well rested you are and how well you function depend not just on your total sleep time but on how much sleep you get each night and the timing of your sleep stages. The pattern of waking during the day when it is light and sleeping at night when it is dark is a natural part of human life. Only recently have scientists begun to understand the alternating cycle of sleep and waking, and how it is related to daylight and darkness.

A key factor in how human sleep is regulated is exposure to light or to darkness. Exposure to light stimulates a nerve pathway from the retina in the eye to an area in the brain called the hypothalamus. There, a special center called the suprachiasmatic nucleus (SCN) initiates signals to other parts of the brain that control hormones, body temperature and other functions that play a role in making us feel sleepy or wide awake.

Melatonin is a natural hormone made by your body's pineal (pih-knee-uhl) gland. This is a pea-sized gland located just above the middle of the brain. During the day the pineal is inactive. When the sun goes down and darkness occurs, the pineal is "turned on" by the SCN and begins to actively produce melatonin, which is released into the blood. Usually, this occurs around 9 pm. As a result, melatonin levels in the blood rise sharply and you begin to feel less alert. Sleep becomes more inviting. Melatonin levels in the blood stay elevated for about 12 hours - all through the night - before the light of a new day when they fall back to low daytime levels by about 9 am. Daytime levels of melatonin are barely detectable. The main enemy of melatonin, and therefore of our health is night lighting. The question about it’s effect on sleep has become more urgent recently, considering the presence of different kinds of gadgets in daily life, which are minor sources of light.

Purpose. The main aim is determine the impact of night lighting on the quality and duration of sleep and to identify effective preventive measures. Also the purpose of this study was to validate an experimental model of the usefulness of the sleep architecture of the sleep, and positive mood, to better understand the mechanisms linking insomnia and depression.

Materials and methods: the research involved mentally and physically healthy 50 people of different ages, divided into two groups: the first is experimental, the second is control. Participants in the experimental group did not follow the sleep mode and sleep in areas not protected from the night lighting. Within one month the change in behavior of the two groups was monitored and compared by results of questionnaire HAM. Method proposed by A. Goscin (1973) and coauthors. The questionnaire consists of 30 pairs of the opposite characteristics, in which the subject is asked to evaluate his condition. Each pair is a scale on which the subject notes the severity of the particular specifications of your state.

In addition to the experiment, there was conducted a survey, based on empirical research methods, among students of WKSMU, living in the dormitory, to determine the level of sleep disturbance. The survey attracted 100 respondents.

Results and discussion. It is revealed that the participants of the experimental group are more susceptible to emotional pressure, react aggressively to negative news, also they showed reduced work capacity and chronic fatigue of the organism as a wholein comparison with the control group.

After analyzing the data obtained from the survey, the following results were received: 30% of respondents haven’t got sleep disturbance, 48% have mild sleep disorder, 22% have persistent sleep disturbance.

Conclusion.While light has direct effects on circadian rhythm, there are indirect effects seen across studies. Seasonal affective disorder creates a model in which decreased day length during autumn and winter increases depressive symptoms. A shift in the circadian phase response curve creates a connection between the amount of light in a day (day length) and depressive symptoms in this disorder. Light seems to have therapeutic antidepressant effects when an organism is exposed to it at appropriate times during the circadian rhythm, regulating the sleep-wake cycle.

In addition to mood, learning and memory become impaired when the circadian system shifts due to light stimuli, which can be seen in studies modeling jet lag and shift work situations. Frontal and parietal lobe areas involved in working memory have been implicated in melanopsin responses to light information.

In response to light exposure, alertness levels can increase as a result of suppression of melatonin secretion. A linear relationship has been found between alerting effects of light and activation in the posterior hypothalamus.

Disruption of circadian rhythm as a result of light also produces changes in metabolism.

Dark therapy before bedtime, where light that triggers melanopsin receptors is filtered out with eyewear, is considered an effective method to promote earlier production of melatoninand improve sleep.

Every person should treat sleep carefully to recover fully and daily follow the simple recommendations:

1. Sleep in total darkness with blackout curtains or blinds in window openings to avoid penetration of the street light into the room.

2. In the absence of the ability to create total darkness, use a sleep mask.

3. Choosing a night lamp, give preference to red light but not too bright.

4. Put all the gadgets away from the bed.

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