Sleep is one of the most important functions for humans. Sleep is often considered essential than food because it helps our body repair and heals itself. Without sleep, our energy resources get depleted, our brains fail to function normally, and our productivity suffers. Lack of sleep over an extended period also leads to various kinds of health ailments.
More important than sleep itself is the sleep-wake cycle. Although sleep is necessary, it doesn’t mean a person can sleep at any time during the day. For instance, it isn’t all right to stay awake at night and sleep at work. Feeling sleepy when the person is supposed to stay awake is a sign of lack of sleep, and may even indicate a sleep disorder. Excessive sleepiness is also one of the biggest causes of road accidents.
Lack of sleep is often caused because of a busy work schedule and lifestyle. But in some cases, it could also be because of an underlying disorder. Sleep disorders often go undiagnosed, but in order to understand sleep disorders, we have to understand the factors affecting sleep.
What Is the Role of Sleep Hormones?
The normal sleep-wake cycle in living is called the circadian rhythm. In humans, this cycle is influenced by hormones to a great extent, and also adjusted according to external cues. Daylight is often the biggest cue for the human brain to wake up and get to work. In nocturnal beings, like owls and bats, daylight indicates its time to go to sleep. These cues generate from the hypothalamus of the forebrain and naturally synchronize or reset according to the 24-hour rotation cycle of the Earth.
The most important hormones affected by this natural sleep-wake cycle are melatonin and cortisol. Melatonin is entirely dependent on the circadian rhythm. Produced in the pineal gland in the brain, this hormone lowers body temperature and causes drowsiness, indicating it’s time for sleep.
Since humans are diurnal beings, they are supposed to be naturally active during the daytime and sleep during the night. For sleep to occur at the right time, the production of melatonin is highly important. Melatonin normally is produced between 8 pm and 9 pm and stops being produced between 7 am, and 8 am in the morning. This period clearly marks the time when we should be ending the day’s work and getting ready for bed. Melatonin is absent (or minimal) during the daytime.
How Does Melatonin Work?
Simply put, melatonin is the hormone responsible for drowsiness and sleep. It is what makes us tired and sleepy and indicates its time to rest. Melatonin is the hormone that regulates the sleep-wake cycle. Because melatonin production is absent during the day, the brains understand it has to stay awake and active. Melatonin production signals to the brain that it’s time for sleep, whether it’s day or night.
A vital factor in sleep regulation is exposure to light or darkness. When we are exposed to bright lights, a special region in the hypothalamus called the suprachiasmatic nucleus (SCN) sends a signal to other parts of the brain that it’s time to get up and be active. This includes a rise in core body temperature and the release of the stimulating hormone cortisol. During this phase, melatonin production is absent.
Melatonin is often called the Dracula of hormones because it is produced only after dark. Even artificial bright lights have been found to hinder the production of melatonin. Most sleep problems are caused because of disrupted melatonin production, although it is hardly diagnosed. In fact, the primary cause for sleep disorders is always something related to melatonin levels.
What Causes Excess Melatonin Production?
As we have already seen, normal melatonin production is what sleep depends on. A person with a healthy sleep-wake cycle has normal melatonin levels. But quite often, people may suffer from abnormal melatonin levels, leading to various sleep and hormonal disorders. Since melatonin is a hormone, it is interconnected with other hormones in the body. When melatonin production is disrupted or elevated, the rest of the hormones are also affected, resulting in various disorders of the system.
An elevated level of melatonin isn’t unusual. In fact, a lot of people suffer from naturally elevated melatonin production. This is most noticeable during certain times of the year. An increased melatonin level is characterized by sleep disturbances and extreme tiredness. Other symptoms of elevated melatonin levels include:
- Difficulty waking up in the morning
- Excess daytime sleepiness
- Fatigue and lethargy
- Low body temperature
- Depression and anxiety
- Foggy memory
What Affects Melatonin Production?
Too Little Sunlight
Spending a lot of time away from sunlight has been found to cause elevated melatonin levels. This is most noticeable in the darker months of winter when there is little sunlight around. This is when melatonin production rises because the brain thinks it is always time for sleep. An elevated level of melatonin is the biggest reason behind seasonal affective disorder (SAD), most noticeable during autumn and winter when days are shorter and darker.
Like all hormones, melatonin is also metabolized in the liver. If there is an excess of any hormone, the liver helps eliminate it from the system. But when the liver function is abnormal, it hinders the removal of the excess hormone from the system. This is why liver dysfunction can lead to an increased level of melatonin in the system, causing excessive sleepiness and fatigue during the daytime.
High Intake of Vitamins B3 or B6
Low levels of vitamins B3 or B6 are often responsible for lack of sleep. But when the intake of these vitamins becomes more than normal, it can lead to excess melatonin production.
Certain antidepressants mimic sleep, causing drowsiness and fatigue. This is because antidepressants are supposed to calm down the brain and help the person sleep. Because depression makes the brain overworked and the nervous system overwhelmed, antidepressants make the melatonin production rise and cause sleep.
Once the root cause of the elevated melatonin levels has been found, it can be corrected by several means, such as spending time outdoors in the sun or improving the liver function.
What Causes Low Melatonin Levels?
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