Why Are Cluster Headaches Affected by the Seasons?
Cluster headaches are the most common form of the trigeminal autonomic cephalalgias. This fascinating neurological disorder causes bouts of extreme, stabbing pain centered around the eye and temple that peak within a few minutes. They are nicknamed “suicide headaches” because of their severity. One characteristic that makes this condition so interesting is that the attacks tend to occur at the same time every day.
These attacks can happen at the same time each day, up to 8 times a day or as few as once every other day. Some clusterheads can set their watch by their attacks, and have anxiety or fear leading up to those times. What’s more, attacks frequently occur at night when transitioning between rapid eye movement (REM) sleep and another sleep stage, which robs clusterheads of their rest and, often, sanity.
Episodic patients typically go into a cycle of attacks when the seasons change, particularly around the solstices when the longest and shortest days of the year occur and also around the equinoxes when we change our clocks for daylight savings time.
Why cluster headaches are linked to seasonal changes is likely due to the amount of daylight that occurs. Seasonal shifts make nights shorter and days longer or vice versa which can disrupt our sleep cycles leading to attacks.
March 21st is the European day for cluster headache awareness because of the spring equinox when “episodics” are more likely to experience attacks. Cluster headache patients, or “clusterheads,” are more likely to go into an episodic cycle (chronic patients may go into a high cycle) in the spring and fall as well as January and February when the days are shortest or July and August when the days are longest. Because of the link between cluster headaches and the seasons, the disorder can be mistaken for allergies or sinusitis.
The link between cluster headaches and seasons, time of day, and sleep cycles points researchers to the hypothalamus—a small area of the brain that regulates the body’s biological clock, hormones, and circadian rhythms.
How Your Brain Changes with the Seasons
The human body can be a working piece of art that usually functions in a healthy, balanced manner effortlessly, but dysfunction in a part of the brain the size of an almond called the hypothalamus is enough to create a cascading impact on the entire body. With cluster headaches, it’s believed that there is a periodic derangement of the hypothalamus that causes the attacks, but the how and why are still not understood.
The hypothalamus maintains homeostasis (healthy balance) in the body. It connects to the nervous and endocrine systems to regulate body functions, including temperature, hunger, thirst, emotions, sex drive, blood pressure, heart rate, and sleep cycles. This tiny portion of the brain nestled between the pituitary gland and thalamus plays a critical role in the body. When other areas of the body send alerts to the hypothalamus that something is unbalanced, it responds by sending the hormone related to that problem into the bloodstream.
Hypothalamic dysfunction or disease can be genetic or caused by head trauma or other factors. Although the cause of cluster headaches is still unknown, there are ongoing genetic studies. Soldiers with traumatic brain injuries can develop cluster headaches. Still, the question is, would they have gotten cluster headaches anyway and the head trauma sped up development, or was it caused by the head trauma?
Biological Clocks & Your Master Clock
The brain has an innate timing device, or biological clock, made of proteins that are found in most tissues and organs in not only humans but also in fungi, fruit flies, mice, and other organisms. Humans also have a “master clock,” which has around 20,000 neurons that form a complicated structure called the suprachiasmatic nucleus, or SCN. The SCN lives inside the hypothalamus and receives input directly from the eyes. When the seasons change and we lose or gain sunlight, the brain responds to those environmental cues by changing the master clock in relation to our circadian rhythms.
The SCN produces the hormone melatonin which helps us sleep. This group of neurons reacts to light signals from the eyes and creates more melatonin at night when there is less light, making us sleepy. A 2002 study published in the Canadian Journal of Neurological Science found abnormalities in the melatonin secretion and cortisol levels in cluster headache patients. Melatonin supplements are commonly used as a preventive treatment for cluster headaches to avoid nocturnal attacks.
Circadian rhythms are regulated by the hypothalamus and change based on a daily cycle that is physical, mental, and behavioral. Our bodies use natural factors to create circadian rhythms, but environmental signals, particularly daylight, lead to changes that cause genes to turn off or on. Shifts in the seasons, namely the amount of sunlight each day, can reset our biological clocks and circadian rhythms as well as slow down or speed up the process.
When these seasonal shifts happen, our sleep cycles, hormone levels, body temperature, and even eating habits are affected. These irregular rhythms are linked not only to cluster headaches but to sleep disorders, mental health, diabetes, and obesity.
Sleep patterns are determined by our circadian rhythms, which strengthen the connection with cluster headaches because of the night time attacks that wake clusterheads from REM sleep or “dream sleep.” Some clusterheads compare it to Nightmare on Elm Street, where Freddy Krueger waits for a victim to reach dream sleep and then sinks one of his finger knives deep into their eye.
Brain Dysfunction in Cluster Headaches During Seasonal Shifts
Men, women, and even children with cluster headaches often live in fear of the changing seasons. They may avoid making plans each March because they know they’ll have attacks several times a day or dread spring and fall. For chronic patients, they brace themselves for an increase in frequency, with sometimes a doubling of the number of daily attacks. Some have even gone so far as to move closer to the equator to avoid environmental changes. However, even in the absence of four seasons, the biological rhythms in the body that instigate cluster headaches still occur. That happens with other species too. Migratory birds kept in controlled environments still exhibited seasonal behavioral changes due to their circadian rhythms.
There are a few tactics clusterheads have found to lessen their chances of going into an episodic cycle or experiencing more attacks than usual during seasonal shifts. One option is adhering to a strict sleep-wake cycle where they go to sleep within the same 30-minute window each night and avoid spikes of stress. Changes in lifestyle can help or hurt. Disruptions to sleep schedule, traveling through several time zones, or other changes can cause cluster attacks to occur more frequently.
Neurologists and headache specialists often have episodic cluster patients start taking preventive medication such as topiramate (Topamax), verapamil, or divalproex sodium (Depakote) a few weeks before the new season or expected time for attacks. Clusterheads typically avoid the most common triggers during this time, which include alcohol, elevation changes, naps, heat, and stress.
Cluster headaches are debilitating and not only upend the lives of patients when the seasons change but year-round for those who are chronic. While there are effective treatments for the attacks, including high-flow oxygen, sumatriptan injections, and occipital nerve blocks, the most promising seems to be psilocybin mushrooms—organisms that also have biological clocks.
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