Keeping your circadian rhythm in time
Like any clock, the one that lives inside us can cause trouble if it gets out of sync.
Called the circadian rhythm, the body’s 24-hour clock is linked to the rotation of the earth. Circadian rhythms regulate the sleep-wake cycle and other essential physiological processes.
It’s kicked off by the first glimpse of morning light — ideally sunlight — which signals the brain to wake up, says Dr. KyoungBin Im, a physician with UCI Health Sleep Medicine Services.
“A region in the hypothalamus receives the light signal via the optic pathway, which processes this signal and coordinates sleep timing, hormone release and a change in body temperature,” says Im.
When night falls, our internal clock tells the body to release melatonin, a natural hormone that helps start and maintain the sleep process, which is vital for good health.
“Sleep occurs most efficiently when this circadian timing aligns with a drive to sleep that increases the longer we are awake," he says.
Common circadian disruptors
Like a clock, the circadian rhythm should move forward consistently.
Natural light first thing in the morning can get the body’s clock moving. But nighttime light from televisions, electronic screens and lamps slow the circadian rhythm down.
“When used at night, screens with bright light can suppress the release of melatonin and delay sleep,” says Im, who has advanced training in the diagnosis and treatment of a variety of causes that can lead to poor quality sleep.
Light exposure at night isn’t the only thing that can disrupt the circadian rhythm and delay the body’s vital sleep phase.
Other disruptors include:
- Insufficient light exposure during the day
- Irregular sleep schedules
- Night shift work
- Travel across time zones
- Repeated late night meals
Consequences of disruption
Disrupting one’s circadian rhythm can lead to more than a night of poor sleep. It can trigger a series of health problems.
“Long-term disruption has been linked to an increased risk of certain cancers and an overall decline in health, particularly in shift workers,” Im notes.
Research at the UC Irvine School of Medicine published in Nature Cancer has linked circadian disruption with the development of colon and rectal cancers.
The study, a comprehensive overview of circadian clock misalignment, found that exposure to constant artificial light at night or chronic jet lag increased the burden of colorectal cancer in mouse models.
In particular, the researchers highlighted "the disruption of the internal circadian clock and external cues through exposure to light at night and erratic eating patterns, and cancer risk, with a particular focus on early-onset colorectal cancer."
Earlier studies at UC Irvine have also linked circadian disruption to changes in the gut microbiome and intestinal barrier that sped up the development of colorectal cancers.
An out-of-sync circadian rhythm is also linked with:
- High blood pressure
- Irritability
- Metabolic disturbances
- Mood instability
- Obesity
- Reduced stress tolerance
- Type 2 diabetes
Keeping a healthy rhythm
Maintaining a consistent sleep-wake schedule is one of the most critical strategies for a healthy circadian rhythm.
Everything else should reinforce it, Im says. That includes:
- Exposing yourself to bright light first thing in the morning
- Minimizing exposure to bright light in the evening
- Keeping daily routines, physical activity and mealtimes consistent
- Sleeping in a dark, quiet, cool environment
Signs of a circadian problem
Im recommends consulting with your primary care physician if your sleep timing is consistently delayed or irregular despite routine habits.
"Excessive daytime sleepiness or impaired daily functioning are also important indicators,” he says. If sleep disturbances are accompanied by mood symptoms such as depression or anxiety, further assessment is warranted.
“A physical evaluation can help identify circadian rhythm sleep disorders or other underlying sleep conditions, such as sleep apnea or acid reflux.”
For more information or to schedule an appointment with UCI Health Sleep Medicine Services, call 714-509-2230.