What is the key to looking younger? Try not to smile as often, a study suggests.

It is recognized that frequent smiling and laughing can be causes of fine lines and wrinkles on the face, commonly referred to as “smile lines.” However, a study proves people identify individuals with smiling faces as older than those with calm or surprised facial expressions, while their perceptions are the opposite.

Researchers showed participants various photos of people with happy, smiling faces and asked them to compare the pictures to others with straight and surprised faces on the basis of age. According to the findings, published in the journal Psychonomic Bulletin and Review, participants thought the smiling faces were two years older than the straight and surprised faces. Those with a surprised look were consistently rated younger.

There is a simple explanation for this finding: When people smile, they appear slightly older because wrinkles form around their eyes due to their expression. On the other hand, a surprised or confused look smooths wrinkles, causing a more youthful appearance.

But Dr. David Kemp, a psychiatrist at Advocate Christ Medical Center in Oak Lawn, Ill., and co-medical director of the behavioral health service line for Advocate Health Care, explains, “There are many benefits to frequent smiling. Smiling releases endorphins and has been shown to reduce stress and anxiety. People who smile often are also perceived to be more approachable, attractive and trustworthy.”

In contrast to the results of this study, the participants noted that a smile usually makes someone look younger when asked afterwards about their perceptions. This flawed recollection shows that people can feel one way and then behave in a totally different way.

The participants were completely oblivious to the fact that during the study, they had “aged” the people who had happy, smiling faces. Although this may seem counterintuitive, their perceptions and opinions were completely opposite to the results.

The U.S. Food and Drug Administration today approved Aimovig (erenumab-aooe) for the preventive treatment of migraine in adults. The treatment is given by once-monthly self-injections. Aimovig is the first FDA-approved preventive migraine treatment in a new class of drugs that work by blocking the activity of calcitonin gene-related peptide, a molecule that is involved in migraine attacks.

“Aimovig provides patients with a novel option for reducing the number of days with migraine,” said Eric Bastings, M.D., deputy director of the Division of Neurology Products in the FDA’s Center for Drug Evaluation and Research. “We need new treatments for this painful and often debilitating condition.” 

Patients often describe migraine headache pain as an intense pulsing or throbbing pain in one area of the head. Additional symptoms include nausea and/or vomiting and sensitivity to light and sound. Approximately one-third of affected individuals can predict the onset of a migraine because it is preceded by an aura – transient sensory or visual disturbances that appear as flashing lights, zig-zag lines or a temporary loss of vision. People with migraine tend to have recurring attacks triggered by a number of different factors, including stress, hormonal changes, bright or flashing lights, lack of food or sleep and diet. Migraine is three times more common in women than in men and affects more than 10 percent of people worldwide.

The effectiveness of Aimovig for the preventive treatment of migraine was evaluated in three clinical trials. The first study included 955 participants with a history of episodic migraine and compared Aimovig to placebo. Over the course of six months, Aimovig-treated patients experienced, on average, one to two fewer monthly migraine days than those on placebo. The second study included 577 patients with a history of episodic migraine and compared Aimovig to placebo. Over the course of three months, Aimovig-treated patients experienced, on average, one fewer migraine day per month than those on placebo. The third study evaluated 667 patients with a history of chronic migraine and compared Aimovig to placebo. In that study, over the course of three months, patients treated with Aimovig experienced, on average, 2 ½ fewer monthly migraine days than those receiving placebo. 

The most common side effects that patients in the clinical trials reported were injection site reactions and constipation. 

Consider the scenario. You're driving on a long, straight stretch of country highway at about 2pm on a sunny afternoon, and you're desperately keen to reach your destination. You're trying to stay alert and attentive, but sleep pressure is building up.

In response you yawn, sit up straighter in your seat, possibly fidget around a little and engage in other mannerisms that may increase your level of arousal.

Is this the purpose of yawning? Yawning is generally triggered by several things, including tiredness, fever, stress, drugs, social and other psychological cues. These are generally well documented and vary between individuals.

The question of why we yawn evokes a surprising amount of controversy for what is a relatively minor field of study. We don't have evidence that can point us to the exact purpose of yawning.

But there are several theories about the purpose of yawning. These include increasing alertness, cooling the brain, and the evolutionary theory of alerting others in your group that you're too tired to keep watch, and someone else should take over.

1. Helps us wake up

Yawning is known to increase with drowsiness. This has led to the arousal hypothesis of yawning. Associated with the yawning are increased movement and stretching behaviour. The increased fidgeting behaviour may help maintain vigilance as sleep pressure builds.

Also, specific muscles in the ear (the tensor tympani muscles) are activated during yawning. This leads to a resetting of the range of movement and sensitivity of the eardrum and hearing, which increases our ability to monitor the world around us after we may have tuned out before the yawn.

Additionally, the opening and flushing of the eyes will probably lead to an increase in visual alertness.

2. Cools the brain

Another theory for why we yawn is the thermoregulatory hypothesis. This suggests that yawning cools the brain. Yawning causes a deep inhalation that draws cool air into the mouth, which then cools the blood going to the brain.

Proponents of this theory claim a rise in brain temperature is observed prior to yawning, with a decrease in temperature seen after the yawn.

But the research report that gave rise to this theory only shows excessive yawning may occur during an increase in brain and body temperature. It doesn't suggest this has a cooling purpose.

Increased yawning rates are seen when fevers have been experimentally induced, which does suggest a correlation between body warming and yawning. But there is no clear evidence it leads to body cooling – just that body warming seems to be a trigger for yawning.

3. Sentry duty

Yawning-like behaviour has been observed in almost all vertebrates, suggesting that the reflex is ancient. The evolutionary based behavioural hypothesis draws on humans being social animals. When we are vulnerable to an attack from another species, a function of the group is to protect each other.

Part of our group contract has included sharing sentry duties, and there is evidence from other social animals of yawning or stretching signals when individuals are becoming lower in arousal or vigilance. This is important for changing activities to prevent the watch from slipping, or to indicate the need for another sentry.

Neuroscience explanations

The yawning reflex involves many structures in the brain.

One study that scanned the brains of those who were prone to contagious yawning found activation in the ventromedial prefrontal cortex of the brain. This brain region is associated with decision-making. Damage to this region is also associated with loss of empathy.

Stimulation of a particular region of the hypothalamus, which contains neurons with oxytocin, causes yawning behaviour in rodents. Oxytocin is a hormone associated with social bonding and mental health.

Injecting oxytocin into various regions of the brain stem causes yawning, too.These include the hippocampus (associated with learning and memory), ventral tegmental area (associated with the release of dopamine, the happy hormone) and the amygdala (associated with stress and emotions). Blocking the oxytocin receptors here prevents that effect.

Patients with Parkinson's disease don't yawn as frequently as others, which may be related to low dopamine levels. Dopamine replacement has been documented to increase yawning.

Similarly, cortisol, the hormone that increases with stress, is known to trigger yawning, while removal of the adrenal gland (which releases cortisol) prevents yawing behavior. This suggests that stress might play a role in triggering yawning, which could be why your dog may yawn so much on long car trips.

So, it seems yawning is somehow related to empathy, stress and dopamine release.

Why is it contagious?

Chances are you've yawned at least once while reading this article. Yawning is a contagious behavior and seeing someone yawn often causes us to yawn as well. But the only theory that's been suggested here is that susceptibility to contagious yawning is correlated with someone's level of empathy.

It is interesting to note, then, that there is decreased contagious yawning among people on the autism spectrum, and people who have high psychopathic tendency. And dogs, considered to be highly empathetic animals, can catch human yawns too.

Overall, neuroscientists have developed a clear idea of a wide range of triggers for yawning, and we have a very detailed picture of the mechanism underlying yawning behavior. But the functional purpose of yawning remains elusive.

Back to our road trip, the yawning may be a physiological cue as the competition between vigilance and sleep pressure begins to favor drowsiness. But the overwhelming message is that sleep is winning and encouraging the driver to pull over for a break, and it shouldn't be ignored.