Circadian Rhythm Sleep Disorders
Circadian rhythm is a an innate biologic feature of living organisms that relates to time and life functions. Generally, this rhythm is based on a 24-hour period.
Circadian Rhythm Sleep Disorders refer to disruptions in the timing of sleep and wake and the consequences that result form the disruption. We all have an internal clock that regulates certain biological functions over a 24-hour period. That clock is referred to as your circadian rhythm..
As with many body functions, your circadian rhythm can get out of alignment for a variety of reasons. For example, the demands of a job, newborn baby or travel can disrupt your body clock. When your internal rhythm is off, it can affect your sleep as well as your wake time.
What is a Circadian Rhythm?
We all have an internal clock that regulates certain biological functions over a 24-hour period. That clock is referred to as your circadian rhythm. Patterns of hormone production, appetite, and cell regeneration are associated with a person’s circadian rhythm, and circadian rhythm disorders can play a significant role in disrupting your sleep-wake cycle.
People have a circadian rhythm that involves being awake during the daytime and sleeping at night. Certain factors affect your circadian rhythm including melatonin production. Melatonin is a hormone in the body that helps regulate sleep. Melatonin production is affected by sunlight. When you’re exposed to light, melatonin levels are low. But when light decreases, such as in the evening, your body makes more melatonin, which in turn makes you sleepy.
Keep in mind; there are individual variations in a person’s internal clock. For example, you might feel you are naturally a morning person, or maybe you consider yourself a night owl.
Types of Circadian Rhythm Sleep Disorders
There are several circadian rhythm disorders including the following:
- Jet Lag: Jet lag is probably one of the best known circadian rhythm disorders. Jet lag is caused by changing time zones, which can disrupt light cues and regular bedtimes. In most cases, jet lag is temporary and regular sleep patterns return.
- Sleep Shift Disorder: Shift work disorder involves problems sleeping due to your work schedule. In most cases, it occurs due to working overnight or rotating shifts. What happens is when you work overnight, your body needs to stay awake, which goes against your natural circadian rhythm. The conflict between what your internal clock wants to do and what you are forcing yourself to do disrupts normal sleep.
- Delayed Sleep Phase Syndrome: Delayed sleep phase syndrome involves the inability to fall asleep at what is considered conventional bedtimes. For example, people with delayed sleep phase syndrome may not fall asleep until 2 or 3 am. Since bedtimes are much later than typical, people with the syndrome usually wake up later in the morning. The problem for people with delayed sleep phase syndrome is their sleep pattern may not match their school or work start time, which leads to excessive daytime sleepiness. The cause of delayed sleep phase syndrome is not entirely understood, but it is more common in teens.
- Advanced Sleep Phase Disorder: Advanced sleep phase disorder is the opposite of delayed sleep phase syndrome. It involves problems staying awake during conventional or socially acceptable times. For example, people with advanced sleep phase syndrome may fall asleep at 7-8 pm and wake up very early at 3-4 am. The cause of advanced sleep phase syndrome has not been identified, but it occurs more commonly in the elderly.
- Non-24 Hour Sleep-Wake Disorder: People with Non-24 Hour sleep wake disorder have a sleep-wake cycle that is longer than 24 hours. Their sleep and rise times drift a little later each night. Sleep times continue to change and eventually may go all the way around the clock. The condition is most common in people who are blind. It may occur in blind people due to lack of light and dark patterns to regulate sleep.