The Dawn of a New Day

 

When the child of morning, rosy-fingered Dawn, appeared, Odysseus rose and led the way to the place of assembly, which was near the ships.

Book VIII, The Odyssey

Homer

 

The phrase “rosy-fingered dawn” is an epithet (a descriptive term) used many times by Homer in both the Iliad and the Odyssey to say, “the break of day”. The term also signifies a fresh start to a new day and a tribute to the trials and tribulations of the day. How does the body handle the “rosy-fingered dawn” and rising from sleep to face a new day? What physiologic changes occur and how do those changes impact heart health?

 

The human body ticks to a 24-hour clock. This clock determines changes in our bodily functions which guide us between a rest stage (sleep) and an active stage. Our internal rhythms are synchronized with the world through interactions with light. These variations are called circadian rhythms (the term circadian is from Latin, circa which means around and dies which means day; around the day). As the rosy-fingered dawn breaks, we sense the presence of light. This results in the secretion of a number of hormones which serve to rouse us, “rev” us up, to get ready for a new day. The hormones include adrenaline and cortisol, which result in an increase in blood pressure and heart rate, increase our wakefulness, increase body temperature and get us ready to be become active. On the other hand, as light fades, the body secretes melatonin and decreases adrenaline and cortisol, getting us ready for the rest phase, sleep. Disruptions to the well-controlled circadian rhythm can lead to various chronic illnesses including heart disease. 

 

Circadian rhythms are controlled by a number of biological clocks. A central clock is located deep in the brain and regulates the clocks located throughout the body. These peripheral clocks are found in nearly all of the tissues of the body, especially in the gastrointestinal system, the nervous system, the liver and the heart. The circadian clocks are molecules within the cell that provide feedback loops timed to a 24-hour cycle. There are clocks in the heart muscle as well as in the wall of blood vessels. The heart muscle clocks orchestrate cellular processes, ensuring that they occur at the right time of the day. Growth and repair of heart tissue takes place during sleep or rest periods. If this circadian pattern is broken, then cardiac pathology ensues. During a normal day, there are fluctuations of up to 20% in various cardiac parameters. For example, blood pressure is lowest during sleep and highest in the early morning hours.  This is due to the release of the hormones responsible for rousing us at the beginning of the day.  Similarly, the greatest risk for a heart attack or stroke is around 6 AM. This is a direct result of the early morning changes with increased blood pressure and heart rate leading to increased stress with the heart’s blood vessels and an increase in clotting factors caused by the release of hormones. In addition, life threatening arrhythmias and sudden cardiac arrest peak around 6 AM.  

 

Maintaining normal circadian periodicity is important for preventing disease and maximizing longevity. Disruption of the normal circadian rhythm is detrimental and leads to a variety of chronic illnesses. Disruption can be genetic, environmental or behavioral. Irregular sleep and eating schedules misalign the clocks. It is important to keep sleep timed with lack of light, i.e. night-time. Irregular sleep schedules throw off the biological clocks so they can’t synchronize properly with the light-dark cycle. Changes such as jet lag and daylight savings time can disturb internal clocks and lead to cognitive impairment and increased risk for heart attack.  Shift workers who sleep during daytime are especially prone to circadian disturbances. Shift work is a risk factor for heart disease, diabetes, obesity and hypertension. It increases cholesterol and triglyceride levels and increase inflammation. Sleep timing is important as well. Evening types, people who have later wake up and bedtimes, are at increased risk compared to morning people. Evening types have a higher incidence of cardiac disease, diabetes and obesity. Therefore, it is important to keep a regular sleep schedule. Meal timing is another factor as food serves to synchronize the biological clocks. Eating late at night also leads to cardiac disease, diabetes, obesity and high cholesterol. Shifting food toward the beginning of the day reduces those risks. This was proven in a recent study. Late eaters, people whose largest meal of the day was after 12:38 PM, had higher risk for obesity than people whose main meal is at lunch time. Having smaller meals throughout the day was better than eating three “square” meals. In addition, intermittent fasting, food intake restricted to early morning to 6 PM with an overnight fast, can reduce weight and protect against metabolic disease. 

 

To every rule, there is an exception. In this case, the exception lies in a Blue Zone. Blue Zones are areas around the world where there is exceptional longevity, with many people in the population reaching 100 years of age. Blue Zones have been identified in Japan, Costa Rica, California and on the Mediterranean island of Ikaria, Greece. The Mediterranean lifestyle seems to counter the circadian rhythms noted above. Dinner is served after 9 PM at night and bedtime occurs late as well. In addition, there is a day time siesta, so sleep patterns are irregular. On the other hand, the main meal is lunch. 

 

There are numerous factors involved in greeting many rosy-fingered dawns. Listening to our biologic clocks and following our circadian rhythms can help stave off disease and increase longevity. In order to do this, regular sleep habits and timing sleep patterns to light and dark seem prudent. In addition, shifting caloric intake to earlier in the day, eating smaller meals and doing some overnight fasting will improve the chances of seeing the dawn of a new day. 

 

 

Cold-Hearted

 

CLEOPATRA: Ah, dear, if I be so,
From my cold heart let heaven engender hail,
And poison it in the source

 

The expression cold-hearted means showing no understanding, no feeling towards another. It is unsympathetic, unemotional, uncaring and cruel. If used in a sentence it might look like this: “The cold-hearted landlord evicted the poor family with a sick child”. The first known use of the adjective cold-hearted is in Shakespeare’s play, “Antony and Cleopatra”. Certainly, Cleopatra could be considered cold-hearted due to her various plots to overthrow her brother and rule Egypt. Heart attacks can also be considered cold-hearted. A heart attack does not discriminate; it can affect men or women, young or old, rich or poor. It can strike at any time of the day or night, often without warning. Despite that, heart attacks do have some predictable variation. For example, heart attack risk changes with the season of the year and is associated with extremes of temperature, both hot and cold.  The only known example of Cleopatra’s handwriting is a single Greek work, γίνεσθοι, which she wrote on a papyrus addressed to a tax collector in 33 BC. It translates to, “so be it” or “make it happen”. Heeding the queen’s order, we will now “make it happen” and outline when heart attacks are the most cold-hearted.  

 

A heart attack occurs when a plaque in a heart artery breaks open. When the blood is exposed to foreign material (such as an exposed plaque), it does what it is supposed to do and forms a blood clot within the artery. If the clot totally obstructs the flow of blood, the type of resulting heart attack is called a STEMI (ST elevation myocardial infarction). If there is still some residual blood flow through the blockage and clot, then the heart attack is a nonSTEMI. For both types of heart attack, there is a U-shaped association with temperature. There is an increased risk for heart attack on very cold and on very hot days. Since we are in the throes of winter, we’ll concentrate on the cold weather effects on the heart. An increase in heart attacks and heart attack deaths in the winter was first noticed in the 1930’s. A large database studied heart attacks from the 1980’s and 1990’s and quantified the risk. A seasonal distribution was confirmed; there were 50% more heart attacks in the winter months compared to the summer time. The peak number of cases were in January, followed by February, March, November and December. Another series, also from the 1990’s, concluded that coronary events were 20-40% more likely to happen in the winter and spring versus other times of the year. One other study (1980’s-1990’s) also showed that the month with the highest mortality rate due to a heart attack was January.  Lastly, a study from Minnesota (1979-2002) showed that a temperature below 0 degrees Celsius (32 degrees Fahrenheit) was strongly associated with death due to a heart attack.

 

A lot has changed in the 25 to 30 years since this data was reported. At least two factors have changed significantly. First, heart attack care has vastly improved. Catheterization and coronary stenting during the acute event (especially STEMI) restores blood flow and subsequently fewer patients die from their heart attack. Secondly, there is global warming. Since the 1950’s each decade is hotter than the previous one. Globally, the temperature has risen 0.17 degrees Fahrenheit each decade, with steeper rise since the 1970’s. Has the combination of warmer weather and improvement in cardiac care reduced the risk for having a heart attack in winter? To answer this a group from Germany looked at temperature and heart attacks in two distinct periods, 1987 to 2000 and 2001 to 2014. During those time periods, the average daily maximum temperature rose from 14.5 degrees C (58.1 degrees F) during 1987-2000 to 15.1 degrees C (59.2 degrees F) in 2001-2014. They found no significant decline in cold related heart attacks when comparing the two eras. Heart attack risk remained high with very cold temperature. Another group studied data from five European countries between 1994 and 2010. They also found that cold weather was associated with an increased risk for heart attack, without change over time. With a drop in temperature from 5 degrees C (41 degrees F) to – 5 degrees C (23 degrees F) there is about 20% increased risk for heart attack and cardiac death. Lastly, a study from Taiwan looking at data from 2000 to 2017 showed that below 15 degrees C (59 degrees F), every 1 degree drop in temperature increased the risk for heart attack by 0.9%.

 

The relationship between cold weather and heart attack has been seen across the globe, in different eras, with different populations and with different weather conditions. It even holds up locally. Over the past five years, the month with the second highest risk for STEMI at Robert Wood Johnson Somerset has been January. How does cold affect the heart and who is at risk?   Elderly patients (over 65 years old) are more susceptible to cold related heart attacks than younger people. The highest risk are older patients with hypertension (high blood pressure). Cold weather increases blood pressure and causes spasm of the heart arteries. This leads to an increase in the work load of the heart. Cold weather increases the thickness of the blood, increases clotting factors and increases inflammation. All of the factors can cause a vulnerable heart plaque to open and trigger a heart attack. The winter months also increase the risk for respiratory infections (for example, flu) which act as a trigger for a heart attack. Other cold related factors include less physical activity, weight gain and holiday stress adding to the risk for heart attack in the winter. 

 

For the elderly heart patient, the cold weather can be as deadly as an asp. For those with significant heart disease, here are some cold weather recommendations. Skip strenuous activity outdoors when the temperature (or the wind chill) is below 30 degrees F and do your exercising indoors. When outside, try to cover all exposed skin. Make sure the heating system in the house is working and use it! The World Health Organization suggests keeping the indoor temperature above 68 degrees F. Lastly, relax with a cup of tea by the fire and count the days until spring.