Ever wonder what the best time is to drink your coffee? You probably know it is not a good idea to drink part of your daily dose of caffeine in the afternoon. Especially for those who have problems sleeping. But, do you ever drink your coffee and feel like it just didn’t work? I know I have that feeling sometimes. The explanation for this has to with a concept that I think is extremely interesting but rarely discussed: chronopharmacology.

Chronopharmacology can be defined as the study of the interaction of biological rhythms and drug action. One of the most important biological rhythms is your circadian clock. This endogenous 24 hour clock alters your physiology and behavior in variety of ways but it can also alter many properties of drugs including drug safety (pharmacovigilance), pharmacokinetics, drug efficacy, and perhaps evendrug tolerance. But, what part of the brain produces this 24 hour cycle and what signals does it receive in order for it to do so properly? It has been known for a long time that light is a strongzeitgeber. A zeitgeber is a term used in chronobiology for describing an environmental stimulus that influences biological rhythms. In the case of mammals, light is by far the most powerful. Following the discovery of connections between the retina and hypothalamus (the retinohypothalamic tract), investigations were aimed at the hypothalamus as the putative master clock. Indeed, in some of the most elegant brain lesion experiments, Inouye and Kawamura (1979) provided some of the first evidence demonstrating that the hypothalamus acts as the master clock in controlling the circadian rhythm. By creating an “island” in the brain by methodically cutting the hypothalamus away from any surrounding tissue, the circadian clock was completely lost (Inouye and Kawamura, 1979).
What does that mean? Well, the output of the hypothalamus nucleus (the suprachiasmatic nucleus or SCN) that controls the circadian clock has a variety of functions. The SCN controls your sleep-wake cycle, feeding and energy consumption, sugar homeostasis, and in addition to a few other things it controls your hormones. And, with respect to your alertness, the SCN’s control of cortisol (often referred to as the “stress” hormone) production is extremely important.

Most readers here, especially the ones in science enjoy–and desperately need–their morning coffee. I’ve seen some striking posts (here and here – note the caffeine consumption map with the number of researchers map) on the internet lately showing the correlation between science and caffeine. Not surprisingly to me, wherever there are scientists, there is a lot of caffeine consumed. And, a scientist also happens to be #1 the profession with the greatest caffeine consumption. But, if you are drinking your morning coffee at 8 AM is that really the best time? The circadian rhythm of cortisol production would suggest not.

Drug tolerance is an important subject, especially in the case of caffeine since most of us overuse this drug. Therefore, if we are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it. This is because cortisol production is strongly related to your level of alertness and it just so happens that cortisol peaks for your 24 hour rhythm between 8 and 9 AM on average (Debono et al., 2009). Therefore, you are drinking caffeine at a time when you are already approaching your maximal level of alertness naturally. One of the key principles of pharmacology is use a drug when it is needed (although I’m sure some scientists might argue that caffeine is always needed). Otherwise, we can develop tolerance to a drug administered at the same dose. In other words, the same cup of morning coffee will become less effective and this is probably why I need a shot of espresso in mine now. Although your cortisol levels peak between 8 and 9 AM, there are a few other times where–on average–blood levels peak again and are between noon to 1 PM, and between 5:30 to 6:30 PM. In the morning then, your coffee will probably be the most effective if you enjoy it between 9:30 AM and 11:30 AM, when your cortisol levels are dropping before the next spike. Originally, when I heard a lecture on this topic, the professor said that since light is the strongest zeitgeber he suggested driving into work without sunglasses on. This would allow for stronger signals to be sent along the retinohypothalamic tract to stimulate the SCN and increase your morning cortisol production at a faster rate. I still tend to drive with them on since I feel blinded by the sun in the morning. However, on mornings when it is partially cloudy out and I did not get a lot of sleep, I drive with them off because this will help me feel more alert than if I was shielding what little sunlight was available. I thought this an important post for anyone but especially with the upcomingSociety for Neuroscience annual conference in San Diego. Now us conference attendees should know just when to enjoy their coffee to stay alert for all of the new neuroscience!

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Mastery | Robert Greene

What did Charles Darwin, middling schoolboy and underachieving second son, do to become one of the earliest and greatest naturalists the world has known? What were the similar choices made by Mozart and by Caesar Rodriguez, the U.S. Air Force’s last ace fighter pilot? In Mastery, Robert Greene’s fifth book, he mines the biographies of great historical figures for clues about gaining control over our own lives and destinies. Picking up where The 48 Laws of Power left off, Greene culls years of research and original interviews to blend historical anecdote and psychological insight, distilling the universal ingredients of the world’s masters.

Temple Grandin, Martha Graham, Henry Ford, Buckminster Fuller—all have lessons to offer about how the love for doing one thing exceptionally well can lead to mastery. Yet the secret, Greene maintains, is already in our heads. Debunking long-held cultural myths, he demonstrates just how we, as humans, are hardwired for achievement and supremacy. Fans of Greene’s earlier work and Malcolm Gladwell’sOutliers will eagerly devour this canny and erudite explanation of just what it takes to be great.

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Glassdoor’s list is ordered by a job score the firm gives each position. This score (based on a 5-point scale ranging from 1.0 as very low to 5.0 as very high) is determined by three key factors weighted equally: earning potential, career opportunities rating, and number of open job listings.

Without further ado, here is the list of the top 10 U.S. tech jobs:

Software Engineer
Database Administrator
Product Manager
Data Scientist
Solutions Architect
QA Engineer
Network Engineer
IT Project Manager
Mobile Developer
Sales Engineer
Only the first three tech jobs placed in the top 10 of the full list. Software engineer was #1 in tech, and it placed second overall. Database administrator was second in tech, but seventh overall, and product manager was third in tech, but eighth overall. Software engineer jobs were found to be in highest demand, while solutions architect positions had the highest average annual base salary among tech jobs.

Glassdoor’s report is based on what employees anonymously say about their employer. In this case, job titles that were considered had to have at least 75 salary reports and at least 75 career opportunity ratings shared by U.S.-based employees over the past year. Job openings per job title (normalized to account for similar titles for the same position) were counted by adding up the total number posted on Glassdoor over the past three months.

Here is the full list of 25 best jobs in the U.S.:

Physician Assistant: 4.8 job score, 45,484 job openings, $111,376 average base salary, 3.5 career opportunities rating
Software Engineer: 4.6 job score, 104,828 job openings, $98,074 average base salary, 3.3 career opportunities rating
Business Development Manager: 4.6 job score, 11,616 job openings, $94,907 average base salary, 3.5 career opportunities rating
Human Resources Manager: 4.6 job score, 8,073 job openings, $96,443 average base salary, 3.6 career opportunities rating
Finance Manager: 4.6 job score, 9,728 job openings, $122,865 average base salary, 3.4 career opportunities rating
Marketing Manager: 4.6 job score, 14,647 job openings, $100,130 average base salary, 3.4 career opportunities rating
Database Administrator: 4.5 job score, 9,790 job openings, $97,835 average base salary, 3.4 career opportunities rating
Product Manager: 4.5 job score, 10,294 job openings, $113,363 average base salary, 3.3 career opportunities rating
Data Scientist: 4.4 job score, 3,449 job openings, $104,476 average base salary, 3.8 career opportunities rating
Sales Manager: 4.4 job score, 26,193 job openings, $76,556 average base salary, 3.3 career opportunities rating
Solutions Architect: 4.4 job score, 3,982 job openings, $121,657 average base salary, 3.4 career opportunities rating
Mechanical Engineer: 4.4 job score, 16,065 job openings, $73,015 average base salary, 3.3 career opportunities rating
QA Engineer: 4.3 job score, 26,383 job openings, $77,499 average base salary, 3.2 career opportunities rating
Business Analyst: 4.3 job score, 21,337 job openings, $74,638 average base salary, 3.2 career opportunities rating
Electrical Engineer: 4.3 job score, 10,435 job openings, $76,803 average base salary, 3.3 career opportunities rating
Network Engineer: 4.3 job score, 14,092 job openings, $87,518 average base salary, 3.2 career opportunities rating
Civil Engineer: 4.3 job score, 6,120 job openings, $73,383 average base salary, 3.5 career opportunities rating
Audit Manager: 4.3 job score, 4,585 job openings, $69,271 average base salary, 3.9 career opportunities rating
Physical Therapist: 4.3 job score, 27,579 job openings, $64,806 average base salary, 3.2 career opportunities rating
IT Project Manager: 4.3 job score, 5,700 job openings, $103,710 average base salary, 3.2 career opportunities rating
Client Services Manager: 4.2 job score, 2,377 job openings, $103,736 average base salary, 3.7 career opportunities rating
Supply Chain Manager: 4.2 job score, 3,754 job openings, $83,795 average base salary, 3.4 career opportunities rating
Mobile Developer: 4.2 job score, 4,651 job openings, $79,810 average base salary, 3.3 career opportunities rating
Nurse Practitioner: 4.2 job score, 15,341 job openings, $95,171 average base salary, 3.1 career opportunities rating
Sales Engineer: 4.2 job score, 6,007 job openings, $91,318 average base salary, 3.2 career opportunities rating