Free-running Circadian Rhythm (FCR) : Apollo Health

Free-running Circadian Rhythm is also commonly referred to as an non 24-hour sleep/wake cycle. Even though most people's body clocks run a bit slow or fast and can cause a circadian rhythm sleep problem, they usually have enough of a light or dark signal sometime during the day that keeps their cycle from constantly shifting. However, a small number of people, and in particular 8 out of 10 blind people, have rhythms that constantly cycle at odd hours independent of a normal 24-hour day. This means that every now and then their rhythm is in sync, but most often it is not.

FCR Symptoms

You may experience one or more of the following symptoms:

Cycling or inconsistent sleeplessness that occurs at different times each night.

Periodic episodes every few weeks or during the month where sleep/wake pattern is in sync with 24-hour day.

Lack of energy during the day, feeling tired in the mid day, early afternoon and/or evening.

Alertness and ability to function may also be diminished.

How FCR Affects You

Because your daily cycle, or circadian rhythm does not recognize circadian light/dark cues, you are often awake when you want to sleep and vice versa. Once in a while you can find refreshing sleep for a few nights until your rhythm is again out of sync. A free running sleep/wake cycle causes a great deal of stress physically and mentally because your body's need to function is at odds with your rhythm. When you need to be active and energetic, your body is often producing the wrong withdrawal and sleep hormones. And when you need to sleep, you can't because your body is producing the active hormones and neurotransmitters. Those with Non 24-hour sleep/wake cycles feel as though they suffering from constant jet lag. Those who suffer from Non 24-hour sleep cycles and irregular sleep cycles are more prone to lack of energy and other mood problems.

Treatment Recommendations for FCR

For sighted people, bright morning light should regulate a free running circadian rhythm. If the rhythm is significantly out of sync, it may take a few weeks before the rhythm is regulated. In blind people, 3 - 5 milligrams of melatonin (time-release may be better) at 9 pm can help keep their rhythm in sync, although it is not as effective as bright light. When their cycle is closer to a normal 24-hour day, they only need to take .5 milligrams of melatonin at 9 pm.

It is also very important to provide as many circadian signals or zeitgebers as possible. Regular mealtimes, lower night time temperatures (8° lower) darker evening and dark nights, with very bright morning and daytime light are all helpful. Some studies show that morning bird sounds and high-density negative ionization also play a role in resetting the circadian rhythm.