Going to bed and waking up at about the same time regularly is a simple approach to maintaining a good sleep cycle. This is one of the reasons I fundamentally oppose the daylight saving time changes in falling back and springing ahead biannually. This bizarre time shift essentially knocks everyone off their normal sleep cycle for up to a couple weeks. Such disruption can affect mood, productivity and other health factors. I vote to abolish it.

Now that I have that off my chest, let’s review some basics of how our sleep cycle works. Our basic rhythm is set by the day-night cycle. The light of dawn and the darkness of dusk are the most fundamental, primordial messages that it is time to awaken or to sleep. Melatonin is a brain hormone that increases after dark, but drops by morning. Another neurochemical, adenosine, also cycles creating a pressure to sleep. Core body temperature drops at night, encouraging initiation of sleep. Sleep experts recommend 68 degrees or lower room temperature to optimize sleep.

Our sleep cycle is a balance of a metronomic, physiological circadian cycle, balancing an urge to awake drive and an urge to sleep drive. When these are harmonized we have a healthy sleep process. When they get disconnected by, say, pulling an all-nighter to study for an exam, there is a mismatch leading to an eventual crash and requiring large amounts of caffeine to compensate.

The disruption of our circadian rhythm has largely developed in the past century with the widespread invention and adoption of electric lights which make day and night merge. The light emitting diodes, LEDs, such as we see on computer and phone screens are disruptive to our sleep cycle when we are exposed to them after dark. I found a feature on my phone that changes the blue color to a more sedating orange-yellow tone after a certain time to allow me to check my phone but not disrupt my melatonin cycle.

Another example of disruption of the sleep cycle is jet lag. Our body and brain simply cannot adjust quickly after being stuffed into a flying metal tube and transported across a half dozen or more time zones, especially when we fly east into a different time zone.

Not everyone has the same rhythm. We all know that some people are night owls, preferring to stay up or work at night. Others are morning larks who wake up full of vim and vigor, just as night owls are ready to wind down. This may have evolved as a survival mechanism for our ancestors, ensuring someone was awake in the cave to keep an eye out for marauders and hungry animals.

Our industrial society invented first the factory whistle, then the alarm clock in order to synchronize the sleep wake cycle to the needs of factories and other work places to get everyone to start at the same time. This is challenging to those whose natural cycle doesn’t match this forced cycle.

So from our love affairs with caffeine, light after night, travel, alarm clocks and constant temperatures in our homes, we have interrupted our inborn, natural circadian rhythm resulting in many sleep disorders. We’ll look at some of those next week.

Dr. Victor S. Sierpina is the WD and Laura Nell Nicholson Family Professor of Integrative Medicine and Professor of Family Medicine at UTMB.

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