Understanding the Circadian Rhythm
The circadian rhythm refers to the 24-hour biological characteristics of each person that constantly change over time to regulate the functioning of various systems in the body, such as hormones, body temperature, sleep and wakefulness, etc. The circadian rhythm control center is located in a part of the brain called the hypothalamus. The circadian rhythm works in sync with the operations of other body systems.
The sleep and wake cycle is one cycle where the circadian rhythm plays a significant role. Moreover, there are several other factors that affect sleep and wakefulness, including hormone levels in the bloodstream, melatonin levels, body temperature, and light exposure, to name a few.
For example, when the body temperature drops, there is an increase in the release of melatonin, making us feel sleepy. Conversely, if our body temperature rises, the level of melatonin drops, which wakes us up.
The hormone melatonin plays a significant role in sleep. High levels of melatonin make it easier to fall asleep. Melatonin is produced by the pineal gland using the precursor amino acid tryptophan. Normally, melatonin begins to increase from 10 PM and peaks around 3 AM, gradually decreasing to its lowest point around 7 AM. Melatonin is influenced by light exposure; bright light reduces its production, whereas darkness increases it.
Changes in the Circadian Rhythm
As people age, various factors can cause the circadian rhythm to shift or become irregular, leading to less smooth sleep patterns. This is due to the deterioration of the hypothalamus part of the brain, a decrease in melatonin in the bloodstream, and a decreased response to light.
Data on the amount of light exposure and the duration elderly people spend in sunlight indicate a trend towards less light exposure, especially when cognitive decline starts, and particularly when facing various diseases that necessitate staying in medical facilities. As the amount of daily light exposure changes, so does the sleep cycle, leading such elderly people to frequently wake up in the middle of the night and take naps more often during the day.
Moreover, a common issue among the elderly regarding sleep is what’s often called “sleeping out of sync.” Many visit the doctor reporting they “go to bed early and wake up early.”
The issue of sleeping out of sync, or going to bed earlier than usual, means that as people age, their sleep cycle starts to shift earlier than normal. This also occurs with changes in body temperature; when the body temperature begins to drop earlier than when they were young, making them sleepy earlier. Typically, the body temperature of the elderly begins to drop around 9 – 10 PM, gradually increasing after about 8 hours of sleep and reaching its peak around 3 – 4 AM. Therefore, elderly people tend to go to bed early and wake up earlier than usual, a condition known as Advanced sleep phase syndrome (ASPS).
In middle age, the prevalence of ASPS is about 1%, but as people age into the elderly years, the prevalence of the disease significantly increases, though there is no exact percentage available currently.
Besides, changes in the environment and the amount of daily light exposure, even genetic factors, play a role in this condition.
Required Hours of Sleep
Upon closer inspection, it turns out that the actual amount of sleep “is sufficient.” However, sometimes we want to live like the rest of society, with a sleep-wake cycle like everyone else. So, we try to go to bed later, hoping to wake up later than usual. But in reality, our body’s condition still “resists” or “refuses to change.” That is, our body temperature remains high around 3 to 4 AM. So, eventually, we wake up at the same time, and worse, our sleep duration becomes even shorter. This makes us feel sleep-deprived, feeling sleepy during the day, sometimes dozing off during work or meetings, and eventually, some might start to feel irritated and discontented with life.
Sleeping Out of Sync Can Be Corrected
The best thing to do is what is called a “sleep diary (sleep diary).” It should be done retrospectively for 1 – 2 weeks. Ideally, you should also wear a device called “wrist actigraphy” on your wrist for about 3- 7 days.
Treating Out of Sync Sleep
In reality, this condition does not need treatment if it does not impact daily life. However, for some who are significantly affected by such a sleep cycle, it may be advisable to seek medical attention. Upon arrival at the hospital, an overall assessment and certain tests are conducted to measure melatonin levels in the body and to examine any irregularities in the sleep cycle.
The primary focus of treatment is non-pharmacological. Treatments aim to adjust and strengthen the sleep cycle, including “Bright-light therapy.” For some who also have a melatonin deficiency, medication might be prescribed to increase the hormone levels in the body.
Bright-light therapy is currently considered the best and most effective treatment. It involves increasing bright light exposure at certain times of the day to the patient to delay the sleep time further. Patients are exposed to bright light in the late afternoon or evening for at least 2 hours a day to shift the sleep cycle, which can also adjust body temperature and melatonin levels.
The best source of bright-light therapy is the “sunlight.” Patients should engage in outdoor activities in the late afternoon or evening for 2 hours daily to delay the bedtime further. Normally, light first hits the eyes, so sunglasses should not be worn during these times but rather in the morning and midday to prevent the sleep cycle from shifting earlier. Additionally, there is a device called “Light box,” producing up to 2500 lux of light, which can be very helpful if outdoor activities are not possible, especially for bedridden elderly patients. Regular household light bulbs are not recommended as they do not produce enough brightness to stimulate the elderly’s optic nerves and change the sleep cycle.
It’s evident that the problem of out-of-sync sleep can sometimes negatively affect many people’s daily lives. Therefore, if experiencing such symptoms, consulting a doctor for proper advice is a good option for every elderly person.