For eons of time, we have arisen and gone to sleep with the rising and setting of the sun. Our body clocks have adapted to these daily light and dark signals and use these cues to regulate our sleep and wakefulness across 24hrs.The resulting cycles in physiology and behavior are called circadian rhythms
However, in the age of electrical light available to light up the darkness, our natural sleep patterns are changing due to light exposure in the evenings.
A study by the University of Surrey, in collaboration with and funded by Philips, has investigated how evening indoor light conditions affect sleep and the time needed to fall asleep.
The study has been published in the Journal of Pineal Research “The spectral composition of evening light and individual differences in the suppression of melatonin and delay of sleep in humans.” – Santhi N, Thorne HC, van der Veen DR, Johnsen S, Mills SL, Hommes V, Schlangen LJ, Archer SN, Dijk DJ. J Pineal Res. 2011 Sep 20.