Circadian rhythm: re-syncing with SAD lamps

  • Published
  • By Staff Sgt. Jarad A. Denton
  • 501st Combat Support Wing Public Affairs
The human body keeps time - an evolved internal biological clock, called the Circadian rhythm, that helps people adapt to a 24-hour cycle of day to night.

Unfortunately, these cycles, which are determined by light, temperature and other inputs from the environment, can desynchronize.

This de-synchronization can come in the form of mood changes that occur during the darker months of the year, which is known as Season Affective Disorder. Recently, scientists have begun to understand a correlation between SAD and the amount of natural light a person receives during the day. The less light, the more likely a person will experience the symptoms associated with the disorder.

As a way to positively impact SAD, the 501st Combat Support Wing has introduced special lights that simulate the natural light needed to maintain Circadian rhythm.

"I've had it about three years," Kristina Da Silva E Silva, 423rd Medical Squadron occupational therapist, said. "It may look like it, but it's not just a fluorescent light. The lamp provides a similar effect to getting Vitamin D from the sun."

Commonly referred to as SAD lights, the lamp is specifically designed to impact people suffering from Seasonal Affective Disorder - otherwise known as "Wintertime blues." According to the U.S. National Library of Medicine, SAD is more common in people who live in places with long winter nights, although some cases have been recorded during summer.

"When you get to the latitude we are at, you get less exposure to sunlight during the winter months," said Dr. James Powell, 501st CSW clinical psychologist. "It takes a certain amount of sunlight to keep the body running efficiently. Darker winter months can throw things out of balance."

Da Silva E Silva said she noticed a shift in her normal rhythm and signs of depression in herself after she became a new mother.

"I was feeling really tired and run down," she said. "It was very difficult to get up in the morning. I was constantly hitting snooze and was often late."

Although Da Silva E Silva said her situation as a new parent was a bit more complicated than traditional SAD, the symptoms she experienced were in-line with those of others who suffered from the same disorder. Typically, feelings of hopelessness, unhappiness and irritability build up slowly during the late autumn and winter months. As with other forms of depression, SAD symptoms can evolve into an increased appetite with weight gain, increased sleep, less energy and ability to concentrate, loss of interest in work or other activities, sluggish movements and even social withdrawal.

"I realized I was struggling with depression a bit," she said. "A colleague recommended I try a SAD lamp. After using it I noticed I was sleeping better, more alert and much less tired. I started exercising again."

Da Silva E Silva said the lamp helps regulate the body's internal clock, which can be disrupted when people don't get enough natural light. The Circadian rhythms fail to trigger and the body does not produce the hormones required to feel wide awake.

"It takes a certain amount of sunlight to keep the Circadian rhythm going," said Powell. "When that level isn't reached, people start noticing disruptions in their sleep cycles, which can lead to things like irritability and depression."

Circadian rhythms are controlled by groupings of interacting molecules within cells found throughout the body - called biological clocks. These various clocks are all coordinated and synchronized by a "master clock" called the suprachiasmatic nucleus, which is located in the area of the brain just above the point where the optic nerves from the eyes cross.

The SCN receives information about incoming light from the optic nerves. When there is less light, the SCN instructs the brain to produce more melatonin - a hormone that makes people sleepy. Therefore, an imbalanced Circadian rhythm can directly influence a person's sleep-wake cycle, hormone release, body temperature and other functions.

"The body produces two substances that work in conjunction with Circadian rhythm: melatonin - which helps people fall asleep, and adensosine - which keeps people awake," said Powell. "All night long the body produces adensosine, until the amount stored up exceeds the amount of melatonin in the body. At that point, the person wakes up."

Powell said while people are awake the exact opposite happens: adensosine is destroyed, as melatonin is built up - causing an individual to feel tired. When the Circadian rhythm is out of balance, people can be left feeling tired during the day and sleepless at night.

Using a SAD lamp is one treatment a person can use to restore a normal Circadian rhythm. While it is always best to consult a healthcare provider before utilizing light therapy treatment, Powell usually recommends people sit two to three feet away from the lamp for roughly 30 to 45 minutes. Typically, a person should do this in the early morning, to mimic the sunrise. After about two weeks, Powell said individuals should being to notice a difference in their mood and sleep patterns.

"The light has to go into your retinas," Da Silva E Silva said. "Usage times vary on light strength. For me, when I'm in the office, it's on. Everyone is different, though, and some people are more light sensitive than others."

Currently, the 43 SAD lamps spread between RAF Alconbury, Molesworth and Croughton are all issued to eligible Tricare beneficiaries. However, the process for obtaining one is simple, according to Maxine Ababa, 423rd MDS mental health office administrator.

"If someone wants a lamp, and we have some available, all they have to do is come to Mental Health to request one, and fill out a hand receipt," Ababa said. "We usually check them out in the Fall and ask they be returned no later than the first of May. This gives us time to service them before reissuing them."

Since the 501st CSW does not currently have any available SAD lamps, people may choose to purchase their own. Powell recommends only purchasing lamps operating at 10,000 lux, which is a unit of luminance, equal to one lumen per square meter.

Additionally, while SAD lamps are medical light treatment devices designed to impact the root cause of SAD, dawn simulators and full spectrum and daylight bulbs are not treatment tools. Within the European Union, SAD lamps must be registered with the Medical Devices Agency and conform to its standards.

While SAD lamps may not work for everyone, for Da Silva E Silva it has been extremely beneficial.

"I'm sleeping much easier," Da Silva E Silva said. "I know that if I wasn't exercising or using the SAD lamp I would probably need to be on antidepressants."