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Night owls have increased risk of depression

- which may be caused by lack of melatonin and the presence of toxic substances in the brain

Night owls have increased risk of depressionNight owls stay up late in the evening and get up late in the morning, and they risk depression, according to a new study. In fact, there seems to be a link between the increasing number of people with disturbed 24-hour rhythm who expose themselves to blue light from computer screens and other devices, and who become depressed. Lack of sleep at night and low levels of the hormone melatonin are a burden to the brain and nervous system in several different ways.

The new study was presented at the Endocrine Society’s annual meeting in Orland, Florida. The researchers had analyzed data from 500 people with type-2 diabetes and found that those diabetics who got up late and stayed up late had more symptoms of depression compared with diabetics who went to bed earlier and got up earlier. The correlation between the displaced 24-hour rhythm and depression even increased the risk of other complications in connection with their disease.
Earlier studies have found a link between circadian rhythm disorders and depression. Evidence suggests that diabetics and others may improve their mental and physical health by attempting to maintain a more natural 24-hour rhythm with plenty of light during the day and total darkness at night in the bedroom.
But why is this so important for our nervous system and health? How does blue light affect us at night? And what can we do if it is difficult to change our somewhat unnatural 24-hour rhythm?

The link between light, dark, sleep, and depression

It has been known for ages that there is a link between lack of sleep and depression. Now, the new study points to a direct link between light exposure at night and depressive symptoms.
An animal study conducted by scientists at Ohio State University, the United States, also showed that when mice were exposed to dim lighting all night, they developed signs of depression after a few weeks only. The study also showed changes in the brains of hamsters, more specifically in the hippocampus area, which is where similar changes have been observed in humans.
The researchers conclude that the risk of depression increases in line with exposure to artificial light during night, and they specifically mention bluish LED light from energy-saving bulbs, smartphones, computers, flat screens etc. The problem is that this type of artificial light disturbs the body’s natural melatonin production.

The melatonin production is affected by light and dark

Melatonin plays an essential role in controlling the body’s 24-hour rhythm (circadian rhythm) and a number of general processes. Melatonin is primarily produced in the little pineal gland (corpus pineale) that is situated in the middle of the brain. From here, there is a direct nerve connection to the ganglion cells in the retina of the eye. When we expose ourselves to daylight, the body produces a precursor of melatonin called serotonin. Once it starts to get dark outside, we slowly begin to produce melatonin, which helps us feel drowsy so we can go to sleep. The natural melatonin production therefore depends on the powerful interplay between daylight and the darkness at night, which is what we know as the astronomical day. This is exactly why it is best for us to get plenty of daylight and to sleep in a pitch-dark room.

Melatonin and sleep have many vital functions

Melatonin is determining for our sleep, the period where we digest our food and recharge – physically and mentally. During our deep sleep, our brain is literally flushed and cleared of toxic waste products. Dream sleep, also known as the REM phase of sleep (Rapid Eye Movement), is like a heavy-duty mental cleansing that supports our learning skills, memory, creativity, and good mood. Melatonin is also a powerful antioxidant that helps repair damaged cells during our sleep.

Lack of sleep poisons the brain and increases the risks of many diseases

When we don’t get enough sleep, toxic waste accumulates in the brain, increasing our risk of depression and other neurological diseases such as Alzheimer’s disease and dementia.

Artificial light at night (especially blue LED light) inhibits our melatonin production

The body’s melatonin production is thrown off balance easily if we get too little daylight or expose ourselves to artificial light at night, especially the modern forms of light known from energy-saving LED bulbs, smartphones, and screens.
The explanation lies in the difference between the natural light sources in the course of the day. Morning light, which is bluish, “kick-starts” our circadian rhythm, while the diminishing, reddish evening light signals that it is soon time to go to sleep.
However, in contrast to the old-fashioned incandescent light bulbs that provide an even color spectrum, the new LED light sources radiate strong bluish colors, which the ganglion cells in the eye are highly responsive to. In other words, the bluish flood of lights from energy-saving bulbs and various screens tricks the body into believing that it is morning. This lowers the production of melatonin, which is otherwise needed to fall asleep. That way, we can easily continue using our smartphones and computers because we don’t feel tired, and the result is that we go to sleep too late and don’t sleep long enough.

According to Professor Poul Jennum, who is a sleep researcher, 10-20 percent of Danish adults have permanent sleep problems, while 40% are familiar with the problem. It appears as though the number increases in line with more and more people checking emails, watching TV, and exposing themselves to light from all types of screens.

Glasses that block blue light improve the melatonin production

Studies reveal that sitting in front of a computer screen or any other type of screen for just a few hours in the evening reduces the body’s melatonin production. In fact, it is possible to improve the melatonin production by prioritizing red and yellow light or using glasses that block the blue light rays. Other studies show that people who use glasses that block blue light sleep better and have improved moods. Melatonin supplements may also be worth considering.

Older people produce less melatonin

The older we are, the smaller the pineal gland becomes, and the less melatonin we produce. At the age of 60 years, the melatonin production is only around half of what it was in our 20s.

Melatonin is a natural sleeping pill

A melatonin supplement is a shortcut to natural sleep, as the supplement compensates for a melatonin deficiency that may be caused by heavy light exposure at night, shift work, night shifts, or jet-lag, all of which are able to interfere with the pineal gland’s melatonin production. By taking melatonin, you correct the disturbances in the circadian rhythm, causing the body to believe that it is nighttime, even when this is not the case. That way, a melatonin supplement may help induce natural sleep, which is vital for our health and mood.

Melatonin protects the brain and nervous system in the following ways:

  • Induces natural sleep
  • Supports the self-cleansing mechanisms in the brain
  • Protects the blood-brain barrier, whereby undesired substances are prevented from entering the brain
  • Functions as a powerful antioxidant
  • Protects brain cells against oxidative stress caused by free radicals

References Being a ”Night Owl” Linked to Depression for Those with Diabetes. Published online April 03.2017

Endocrine Society. Late Sleep-wake time preference linked to depression in individuals with diabetes. ScienceDaily. April 2017

Wood B et al. Light level and duration of exposure determine the impact of self-luminous tablets on melatonin suppression. PubMed 2013

Underwood Emily. Sleep: The ultimate Brainwasher? Science/AAAS/News 2013

Graven, Andreas R. For lidt søvn kan give depression. 2014

Licht Cecilie Löe: Depression – biologisk forskning i psykisk sygdom 2007

Pierpaoli Walter, Regelson William. The Melatonin Miracle. Simon and Schuster 1996

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