As humans, our bodies naturally respond to light & dark and are designed to sleep with the rhythms of the sun and moon, we have evolved to fall asleep soon after the setting sun and to awaken at its dawn the following morning. Our sleep has been governed by the sunlight and darkness for many thousands of years, meaning that we have had nine of more hours of sleep each night. We are encoded to respond to light and dark but the invention of the electricity and the lightbulb or artificial light dramatically changed lives, with most of us now sleeping for around than six hours per night leaving most of us exhausted and suffering from a multitude of ailments. Returning to our natural sleeping cycles and natural rhythms can make us energized, calmer & centered, losing the brain fog and many other maladies. Our sleep is time for the rest and rejuvenation of our bodies.
Artificial indoor lighting causes our bodies to disassociate from the natural cycles of light and darkness that would encourage us to sleep. Try mimicking the time of the day by changing the amount of the light in your space, turning down the brightness of light in the evening encourages an earlier bedtime and then sleeping without blackout drapes or shades is best so you can wake up with the dawning sun.
Changing your sleep patterns in synchronization to the cycles of light and darkness will encourage your sleeping and waking rhythms naturally. This gives us more waking hours in the summertime to benefit from spending time outside in the sunshine, think of all the Vitamin D and extra exercise then ensuring the hours of sleep during the winter months when your body needs it most.