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  • The Sound Sleeper

How much of your sleep is hereditary?

Sitting around the Thanksgiving dinner table looking for a good topic of conversation with family? How about asking, “Are you a morning lark or night owl?”

A morning lark (also called an early bird) is an early riser who is in top form in the morning and prefers to go to bed early. A night owl, on the other hand, has a later schedule and is most productive in the afternoon and evening. This is your chronotype — your natural sleep-wake preference for a particular time of day.

About 40 percent of people are “morning types” and 30 percent are “evening types.” The remaining third of us are neutral, not falling at either extreme. Your chronotype is genetic, so finding out family members’ time of day preferences can be interesting — and can clue you in on whether to thank your mother or father for yours.

Since your chronotype is hardwired in your DNA, you can’t change your preference but it does evolve with age. Children generally have an early chronotype, until they become teenagers and shift to a later schedule (now you know why your teenager has a hard time waking up for school in the morning!). Gradually our chronotype shifts to its preferred schedule in adulthood, evolving over time to an earlier schedule as we become older adults.

Understanding your chronotype can help with your decision-making and time management. For example, if you’re a night owl who can’t possibly get to sleep early, you may want a job that doesn’t require an early morning start time. A morning lark might want to schedule presentations for early morning rather than late in the day to take advantage of maximum alert time.

According to a University of Michigan study, morning larks have an easier time adjusting to Daylight Saving Time in the spring — acclimating to the one hour loss in a few days versus more than a week for night owls. However, the researchers found no difference between the two groups in the autumn “fall back” time change.

Genetics strikes again

A number of other sleep characteristics may also be genetic, such as timing of sleep, total daily sleep needs and response to sleep deprivation. One example is the “Natural Short-Sleepers” — those who naturally sleep less than the normal population without any adverse effects. This trait has been found to be genetic in some families.

While sleep apnea is a complex condition influenced by multiple factors, researchers have found a strong genetic component. Inherited craniofacial structure, body fat distribution and/or nervous system control of the upper airway muscles can all factor into developing the condition. Research suggests that the underlying cause of obstructive sleep apnea is about 40 percent attributable to genetics, with the remaining 60 percent environmental or lifestyle-related.

Whatever cards you’re dealt on the sleep front, making sleep your priority can help you lead a healthy, happy life.

Sources: Sleep Foundation; Casale, M et al. (2009) Obstructive sleep apnea syndrome: from phenotype to genetic basis; Redline, S et al. (2000) The genetics of sleep apnea, Sleep Med Rev; Shi, G (2017) et al. Human genetics and sleep behavior, Curr Opin Neurobiol; Tyler, J et al. (2021) Genomic heterogeneity affects the response to Daylight Saving Time. Scientific Reports, 2021; Walker, M (2017) Why We Sleep, Unlocking the Power of Sleep and Dreams.

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