Why the study?
Does bright artificial light exposure alter the rhythms of 6-sulphatoxy melatonin and cortisol excretion in healthy males?
Does bright artificial light exposure alter the rhythms of 6-sulphatoxy melatonin and cortisol excretion in healthy males?
A single 6-hour period of bright artificial light in the evening can phase delay melatonin onset and alter cortisol excretion rates in healthy males.
Evening bright light may phase-delay melatonin onset and sustain cortisol in healthy males; leaves open effects on sleep or cardiometabolic outcomes.
The purpose of this study was to investigate the effect of bright artificial light exposure on the rhythms of 6-sulphatoxy melatonin and cortisol excretion in urine. Six healthy males were exposed to light (greater than 3,000 lux) from 1900 to 0200 h (sunset 1928 h) on one occasion. The artificial light delayed the onset of 6-sulphatoxy melatonin excretion. On the next evening the onset of 6-sulphatoxy melatonin excretion in normal light/darkness was delayed by 1 h. The timing of the peak excretion of cortisol was not affected by the light treatment; however, cortisol excretion rate was maintained at a significantly higher rate in the morning and afternoon after the treatment. These results demonstrate the inhibitory action of high intensity light in humans and suggest that one 6-h period of extra light in the evening can phase delay the melatonin onset.
No takes yet. Share an insight, caveat, or question.
Kennaway et al. (1987) studied this question.
Synapse has enriched 3 closely related papers on similar clinical questions. Consider them for comparative context: