Why Do Cluster Headaches Wake You in the Night?
Cluster headaches follow a distinct pattern. People with the episodic form often go into cluster headache cycles at the same time of year (typically around the Spring and Fall equinoxes), and some can pinpoint it to the exact day. Chronic "clusterheads" go into high cycles during these times too, during which they have an uptick in frequency.
Cluster headache attacks when sleeping
When you're experiencing cluster headache attacks, they often come at the same time(s) of day and a hallmark of the disorder is that clusterheads will typically wake up in the night or from a nap with an attack, begging the question: Why do cluster headaches wake you from sleep? According to neurologists and scientific research, it's because of your circadian rhythms.
What are circadian rhythms?
To understand why cluster headaches attack us when we sleep, you must understand circadian rhythms and a few parts of the brain. Your circadian rhythms are controlled by the hypothalamus and regulate your sleep-wake cycle and biological clock.
The circadian pattern of cluster headaches
The circadian pattern of cluster headaches continues to enamor and confuse researchers, while patients live in fear of the clock. Many clusterheads know the exact times of the day that they will have an attack. Episodics, like myself, are more likely to experience cycles during specific months each year. Personally, my usual months are April and November, and the times are 4 am, 8 am, 2 pm, and 8 pm.
How does the circadian system work?
The circadian system can be traced back to a single cell, according to research by Dr. Mark Burish published in 2018, which creates a "feedback loop," causing other cells to activate and deactivate like clockwork every 24 hours. A central clock governs that peripheral clock in your cells. It has a very long name — Suprachiasmatic nucleus (SCN) —and sounds like it could be from Mary Poppins. The SCN is found in the front portion of the hypothalamus —that almond-shaped part of the brain that also controls hormone regulation, among many other vital jobs. The SCN or central "clock" of your brain is calibrated by sunlight, which then sets the peripheral clocks in your body to their 24-hour cycle.1
Cluster headache cycles
This elaborate system is why you can adapt to a new time zone when you travel and when the seasons change. The SCN is not only impacted by the amount of light but also your temperature, melatonin, exercise, food, and corticosteroids. For episodic cluster headaches, the amount of daylight and melatonin (melatonin supplements are a standard preventive treatment for cluster headache) are key factors because your body follows a circannual pattern to adapt to the changing seasons. During these transitional times when days are shortest or longest, clusterheads experience episodic cycles or high cycles.
Bracing for the next cluster headache cycle
What's fascinating to note, is that even those living nearer the equator who don't experience the four seasons still have cluster headaches during these times of the year. The next equinox is September 22nd, 2020, which means episodic clusterheads around the world are bracing themselves for the next cycle.
Preventive medications for cluster headache
Four of the current preventive medications used to treat cluster headaches impact the circadian rhythms and that feedback loop from the SCN:
- Valproic acid
REM sleep and cluster headaches
I could go on and on about the seasonal impact and exact timing of cluster headache attacks, but let's get back to the sleep aspect. Many of us feel like zombies during a cycle because attacks tend to wake us from REM sleep. Rapid Eye Movement (REM) is the last sleep stage where your eyes move erratically underneath closed eyelids and your breathing changes. (Not to be confused with R.E.M., a decent band from the 80s and 90s.) During this time, brain waves spike, blood pressure rises, and heart rates increase — this is when your dreams occur.
A nightmare on REM street
A close friend of mine likens it to Freddy Kruger, waiting for you to fall asleep so he can slip his knife fingers into your eye socket and temple. In the past, I have set the alarm for every 2-3 hours to prevent myself from going into deep sleep and having an attack. The result is disastrous, leaving some with PTSD-like symptoms when the cycle finally ends. Cluster headache steals from you in the night and makes daytime naps impossible, but why? Well, it goes back to the hypothalamus and the natural hormone melatonin. Melatonin tells your body when it's time to go to sleep. During active cycles, cluster headache patients release lower levels of melatonin at night, which is why supplementation can be an effective preventive treatment.
Sleep and cluster headache research
A 2015 study aimed to analyze the connection between sleep and the severe unilateral pain that is cluster headaches by studying the sleep of 40 cluster headache patients during an active cycle and comparing it to the sleep patterns of 25 controls in a hospital setting. They found no difference in who had sleep apnea between the two groups. However, they did find that the cluster headache patients not only had less REM sleep, but it took them an average of 48 minutes longer to reach the REM sleep stage than the control group.2
What were the results?
The average person hits REM 90-120 minutes after falling asleep, but cluster headache patients took around two hours in this sleep study. Researchers also found that the cluster headache group had half as many arousals as the control and concluded that the study was further proof that the hypothalamus is involved in REM sleep and cluster headaches.
What can you do to prevent cluster headaches from waking you?
There's no way you can avoid REM sleep forever, whether you have episodic or chronic cluster headaches (or are concerned about a knife-fingered nightmare serial killer). Your body needs to cycle through the sleep stages to rest. Stronger people than me have tried this, and it doesn't go well. The best advice I can give aside from the recommended melatonin supplement before bed is to pay attention to your sleep hygiene and go to sleep within the same 30-minute window every night.3 Creating a nightly routine and sticking to it year-round could help when you go into a cluster headache cycle.
P.S. Sleep with your oxygen tank and handy-dandy cluster O2ptimask™ next to the bed so you can abort the nighttime attacks quickly.
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