Circadian Signs Found in Hair Samples

You can find out a lot about a person’s health just by taking a hair sample. Employers and police use hair tests to detect traces of alcohol, cocaine, marijuana, meth and many more oft-abused substances. Your doctor can tell you if you have any vitamin, mineral or nutritional deficiencies from a few dozen strands. And now researchers are learning hair tests can show when we are supposed to sleep and whether our body clocks are off track.

Findings published in the Proceedings of the National Academy of Sciences suggest hair sample testing may help specialists in sleep medicine diagnose circadian rhythm disorders. Hair follicle cells from the head or chin hair contain clock gene expressions. In other words, the amount of the genetic material RNA in your hair shows whether you’re supposed to be alert. Your hair has the most RNA during peak hours.

The Japanese authors repeatedly took hair samples from volunteers as they continued their daily routines. Over the course of three weeks they adjusted their schedule by four hours. Hair samples show their peak activity was still about two hours off, meaning their body clocks weren’t adjusted to the new sleep schedule.

The effect was magnified for rotating shift workers. Their body clock differed from their sleep-wake schedule by an average of five hours.

Beard hair worked best for the tests: researchers needed only three strands to detect circadian rhythms. It took about five head hairs for people with thick hair and up to 20 for thin head hair.

The technique is still in its infancy but has potential for clinical use, the authors argue. Hair samples could potentially tell us our chronotype and diagnose circadian rhythm disorder, jet lag and shift work disorder.

Read more about chronotypes and shift work on the Sleep Education Blog.

Image by Sciencehealth

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Morning Larks Lead Better Careers, Chronotype Expert Claims

The business world wakes up bright and early and the evening types have no choice but to fight their natural inclination to keep up with competition. For this reason it’s the morning types that hold an advantage at the office. The body of research by chronotype expert Christoph Randler suggests people who reach their peak performance in the a.m. hours seem to be better positioned for career success.

Randler was featured this month in the Harvard Business Journal’s “Defend Your Research” series. His latest research concludes morning larks are more likely to be of the “take charge” type. A sample of 367 college students responded to surveys with questions about when they tend to be most energetic and whether they are willing and able to take action to change a situation to their advantage. The students who reported they are at their best in the morning hours more often agreed with proactive statements about themselves.

He said its proactivity that leads to better job performance, greater career success and higher wages. Randler’s earlier studies suggest the advantage starts in school. The morning bell rings bright and early at most schools, and from a young age the morning types benefit. They tend to get better grades, which gets them into better colleges and then nets them better jobs out of school. They’re poised to start work early at a high level of performance once they join the 8 to 5 business world.

Despite how it sounds, evening people aren’t condemned to a life of destitution. Research shows they’re often smarter, creative, more outgoing and have a better sense of humor than their button-down counterparts. They can thrive given a more suitable schedule and environment.

These sweeping statements are a bit of a simplification, Randler admits. Evening types can be proactive and some can slightly shift their daily sleep-wake schedules without difficulty. Other research shows our chronotypes shift towards the mornings as we age. The effect may be due to the adult responsibilities such as working and raising children.

If you don’t know whether you’re a morning or evening type there’s an easy way to tell, Randler states. Evening chronotypes sleep in an average of two hours longer on weekends, while morning chronotypes are up bright and early as usual.

Image by Joey Parsons

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Are the best and brightest natural night owls?

Our society seems to celebrate the ambition of early risers. We tend to admire the person who’s out on a seven mile jog at the crack of dawn or the employee who’s firmly planted at their desk long before everyone else arrives.

The night owl, who sleeps through most of the morning, is viewed as lazy or irresponsible at best, drunks or criminals at worst.

Do we have it all wrong? Evolutionary psychologist Satoshi Kanazawa poses that question in the latest entry in his blog The Scientific Fundamentalist.

He hypothesized the most intelligent American children grow up to sleep in later their peers. The author looked at the possible relationship between early childhood IQ scores and reported bedtimes in early adulthood.

Kanazawa classified children into five categories according to their IQ scores. Children with IQ less than 75 were considered very dull, above 125 were called very bright. Those in the middle of the bell curve, with a score around 100 were considered average.

You can see in the charts below, the higher the childhood IQ scores the more likely the subjects were to stay up later in early adulthood.





While the data suggests the smartest people turn out to be night owls and the least intelligent end up as larks, there might be more to this relationship than the author lets on. In his entry he fails to define early adulthood. If this includes people around the ages of 18-25 there may be some lifestyle factors at play.

College students are notorious for their nocturnal tendencies. Most Americans of above average intelligence pursue some form of higher education. Many of the most gifted go on to get Master’s degrees or PhD’s, extending that lifestyle by 2-6 years.

Those that choose to go straight into the workforce after high school don’t have the luxury of making their own schedule and sleeping in like college students. They jump right into working the typical 8-5, or even early bird hours, in the case of some blue collar jobs like manufacturing.

Regardless of if the hypothesis is true both chronotypes still come with downsides. Evening-types have a higher risk of severe depression symptoms. Larks may never reach a level of maximum performance during the day.

Contrary to traditional wisdom, morning types were found to be no healthier, wealthier, or wiser than night owls.

It’s best to follow your instincts when it comes to your sleep schedule. Trying to switch from night owl to lark may end up cutting into length of sleep, ultimately doing more harm than good.

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Your Sleep Personality Type

A new study examined how your natural sleep preference may be related to your personality type.

The study from Spain involved 862 college students. They were between the ages of 18 and 30.

They completed a short version of the Morningness-Eveningness Questionnaire (MEQ). It measures your circadian “chronotype” – your preferred sleep schedule.

Some people have a circadian clock that makes them “evening types.” These “owls” have a natural tendency to stay up late at night and sleep late in the morning. In contrast “morning types” are “larks” who prefer to go to bed early and wake up early.

The students also completed a short version of the Temperament and Character Inventory (TCI). It measures seven dimensions of personality.

Results show that women had higher TCI scores for harm avoidance, reward dependence and cooperativeness. Men had higher scores for novelty seeking.

How did sleep preference and personality type interact? Evening types had higher scores for novelty seeking. People with this personality type tend to be curious, impulsive and easily bored.

Only men who were evening types had both a lower harm avoidance score and a higher novelty-seeking score. People who are low in harm avoidance tend to be carefree, energetic and outgoing.

Last year a study reported that people who are “evening types” have a higher risk of severe depressive symptoms. Another study suggested that morning types may never reach a level of maximum performance during the day.

Learn more about the lark and owl chronotypes.

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