Human Melatonin Suppression by Light is Intensity Dependent (original) (raw)
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The effect of dim light on suppression of nocturnal melatonin in healthy women and men
Journal of Neural Transmission, 1997
The present study investigated the effect of dim white light on nocturnal plasma melatonin in males and females. Subjects were exposed to light between 2400hr and 0100hr. No significant gender differences were found with both 2001ux (p > 0.1) and 5001ux (p > 0.1) of light. Furthermore the amplitude of the melatonin rhythm was not significantly different with gender. This suggests that at low intensities the melatonin sensitivity to light is not differentially regulated between sexes.
Melatonin Sensitivity to Dim White Light in Affective Disorders
Neuropsychopharmacology, 1999
Both dim and bright light has been shown to suppress the nocturnal secretion of the pineal hormone melatonin. Early reports suggests that an abnormal response to light occurs in patients with bipolar affective disorder, where as patients with major depressive disorder respond similarly to controls. It has been suggested that this abnormal sensitivity of the melatonin response to light could be a trait marker of bipolar affective disorder. However reports lack consistency. Hence, we investigated the melatonin suppression by dim light (200 lux) in patients with bipolar affective disorder, seasonal affective disorder and major depressive disorder. Results suggest that a supersensitive melatonin suppression to light in bipolar affective disorder (p Ͻ .005), and seasonal affective disorder (p Ͻ .05), whereas patients with major depressive disorder display similar suppression to controls. The supersensitivity may be a mechanism where by phase-delayed rhythms, are resynchronised to a new circadian position. Conversely, an abnormality may exist in the pathway from the retina to the suprachiamatic nucleus.
Human melatonin response to light at different times of the night
Psychoneuroendocrinology, 1989
Normal control subjects were examined on three separate occasions with light of sufficient intensity to suppress nocturnal plasma melatonin concentrations. One hour of light was given at each of the following times: (a) 2100-2200h; (b) midnight to 0100h; (c) 040(0-0500h. Melatonin synthesis was just becoming apparent at 2100h. There was significant suppression of melatonin by light when given at midnight-0100h and 0400-0500h, but not when light was given at 2100-2200h. In each case following light, melatonin synthesis was shown to resume, even after light applied in the second half of the dark period (0400-4)500h). A second experiment was undertaken to examine a possible "rebound" in melatonin levels following light given at 2100-2200h. Six further control subjects were exposed to light at this time, and plasma melatonin levels were measured until 0400h. No rebound in melatonin concentrations was observed. These results are compared with other studies of melatonin response to evening light exposure.
Preliminary evidence for spectral opponency in the suppression of melatonin by light in humans
NeuroReport, 2004
Human adult males were exposed to light from blue light emitting diodes (18 lux; 29 mW/cm 2) and from clear mercury vapor lamps (450 lux; 170 mW/cm 2) during night-time experimental sessions. Both conditions suppressed nocturnal melatonin concentrations in blood plasma with the blue light more e¡ective than mercury at melatonin suppression. No additive model incorporating opsin photopigments either alone or in combination could explain the results, but a model incorporating an opponent mechanism was consistent with the present data as well as data from previously published studies. NeuroReport 15:313^316 c 2004 Lippincott Williams & Wilkins.
Biomedical Journal, 2016
Background: Continuous light or darkness has various effects on different systems. In the present research work, the effects of constant light and darkness exposure of male rats and oral administration of exogenous melatonin on the serum levels of melatonin have been studied. Methods: Thirty adult male Wistar rats were divided into six groups of: (1) Control, (2) melatonin, (3) light, (4) light and melatonin, (5) darkness, and (6) darkness and melatonin. All groups were placed according to light conditions for 10 days. Melatonin was administered orally after a period of 10 days to Groups 2, 4, and 6 (10 mg/kg of body weight). Serum levels of melatonin were measured using ELISA. Results: The results showed the significant difference on serum melatonin in darkness, no light, and control groups. Although serum levels of melatonin were different in melatonin groups, the difference is not significant. Conclusions: We concluded that being exposed to continuous darkness leads to an increase in serum melatonin.
Scientific Reports, 2020
The magnitude of nocturnal melatonin suppression depends upon the spectrum, amount, and duration of light exposure. The functional relationship between melatonin suppression and the light spectrum and amount have been previously described. Only one duration-dependent parameter was needed to extend this functional relationship to predict nocturnal melatonin suppression during the early biological night from a variety of published studies. Those predictions suggest that ambient lighting commonly found in North American homes will not suppress melatonin for durations up to 3 h, whereas extended use of self-luminous displays in the home prior to sleep can.
Journal of Biological Rhythms, 2019
The human circadian system is primarily regulated by the 24-h LD cycle incident on the retina, and nocturnal melatonin suppression is a primary outcome measure for characterizing the biological clock’s response to those light exposures. A limited amount of data related to the combined effects of light level, spectrum, and exposure duration on nocturnal melatonin suppression has impeded the development of circadian-effective lighting recommendations and light-treatment methods. The study’s primary goal was to measure nocturnal melatonin suppression for a wide range of light levels (40 to 1000 lux), 2 white light spectra (2700 K and 6500 K), and an extended range of nighttime light exposure durations (0.5 to 3.0 h). The study’s second purpose was to examine whether differences existed between adolescents’ and adults’ circadian sensitivity to these lighting characteristics. The third purpose was to provide an estimate of the absolute threshold for the impact of light on acute melatonin...
The Solid Angle of Light Sources and Its Impact on the Suppression of Melatonin in Humans
Springer eBooks, 2013
Our group conducted a preliminary study to examine the influence of different sizes of light sources, and therefore different illuminance levels, at the retina. Six participants were exposed to two lighting scenarios and saliva samples were collected to determine melatonin levels throughout the experiment. Melatonin levels were analyzed to compare the efficacy of each lighting scenario and its ability to suppress melatonin period. Our data is showing a trend that both lighting scenarios are capable of suppressing melatonin. Moreover, the preliminary data show that the lighting scenario with the large solid angle is more effective at suppressing melatonin compared to the lighting scenario with the small solid angle lighting scenario period. Further testing with a larger patient population will need to be done to prove statistical significance of our findings. Our further studies will repeat this experiment with a larger test group and modifying the time frame between different lighting scenarios period.
Possible Behavioral Consequences of Light-Induced Changes in Melatonin Availabilitya
Annals of the New York Academy of Sciences, 1985
Melatonin is a hormone secreted at night by the human pineal organ. This nocturnal release of melatonin, in humans and other species, is rapidly suppressed by exposure to sufficiently bright light.' Melatonin was first isolated and its structure identified by Lerner and his coworkers over 25 years ago.* Until very recently, however, the effects of this hormone on human behavior had not been closely examined. Some studies had suggested that melatonin had hypnotic-like proper tie^;'.^ others, however, failed to document such effectss The influence of exogenously administered melatonin on animal behavior is still unclear and often contradictory. For example, Holmes and Sugden6 reported that melatonin increased sleep in the rat, whereas Mendelson et al.' have reported a decrease in time spent sleeping after melatonin administration. Other studies with rats have indicated that melatonin has anxiety reducing properties (to the extent that such effects can be inferred from animal behavior).*.9 If melatonin does have different effects on different species this may be attributable to differences in daily patterns of activity displayed by such species (diurnal, nocturnal, or crepuscular).' Although the behavioral effects of melatonin on animals remain uncertain at this time, the effects on humans have recently been clarified. These recent human studies, including one conducted in our laboratory, will be discussed. A possible relationship between light exposure, human alertness, and circadian patterns of activity, as mediated by melatonin, will also be discussed. In these recent human studies melatonin has been administered in various doses, acutely and chronically, a t various times of the day to healthy male and female volunteers. Vollrath et al.." in a double-blind crossover study administered melatonin (1.7 mg) intranasally to six male and four female volunteers. It was observed (apparently based on a self-report questionnaire) that seven subjects fell asleep within 1 or 2 hours of melatonin administration, whereas only one slept after placebo administration. Although standard methods for quantifying sleep or sleepiness (i.e. EEG recordings or standardized self-report mood questionnaires) were not used, the consistency of the findings is strong support for melatonin having hypnotic properties uThis work was supported by NIH Grants 2R01-HD11722 and 2M01-RR00088 as well as dPresent address: Univ.-Kinderklinik. Waehringer Geurtel74-76, A