How to Get In (Circadian) Rhythm

Falling asleep at night or waking up in the morning at the right times can be difficult, especially if you have a lot on your mind or a busy day ahead. Poor sleep can increase stress levels and negatively impacts your physical and mental health over time. Managing stress and prioritizing sleep are important in all stages of life, and they are one of the 8 Healthy Steps to Get Cooperized ™ developed by Kenneth H. Cooper, MD, MPH, Founder and Chairman of Cooper Aerobics.

Sleep medicine patients at Cooper Clinic often share that a common sleep challenge is adjusting to a new time zone when traveling or to the semiannual changes necessitated by going on and off Daylight Saving Time. Sonya L. Merrill, MD, PhD, FACP, Sleep Medicine Physician at Cooper Clinic, shares some helpful insights about how to get back in rhythm on such occasions.

How Does Your Body Know When to Sleep?

The circadian rhythm is the body’s internal clock. It regulates many processes—including sleep and wakefulness, body temperature, hormone release and metabolism. It helps determine when the brain and body are biologically prepared to be awake or asleep.

Light is the most important external cue for sleep and wakefulness. In fact, sleep scientists call it the zeitgeber, the German word for “time giver.” When the retina perceives the absence of light (darkness), it signals the suprachiasmatic nucleus (SCN), the brain’s master clock, which in turn triggers the pineal gland to rev up production of melatonin, the hormone that facilitates sleep onset.

Conversely, when light hits the retina, melatonin production is suppressed. The absence of this sleep-inducing hormone enables us to wake up. This is why it is important to avoid bright light exposure in the evening and allow bright light into our bedroom in the morning.

Disruptions to the Circadian Rhythm

Daylight Saving Time

Daylight Saving Time was originally implemented during World War I in Germany to enhance productivity throughout the year. Working during the extended sunlight hours meant burning less fuel for electricity in the evening and enabled people to work later into the day. It was later adopted in the United States and United Kingdom.

During Daylight Saving Time, the sun rises an hour later, making it harder for you to wake up when you need to. For instance, if you usually wake up at 7:00 a.m., after the spring time change, when the sun rises an hour later, the absence of sunlight at your usual 7:00 a.m. wakeup time may make it difficult to get up when the alarm goes off. The reverse is true at night; because you are exposed to daylight an hour longer in the evening, you may not feel sleepy at your usual bedtime.

To help adjust to the time change in the spring, try to go to sleep a little later three to four days prior to the start of Daylight Saving Time. Likewise, a few days before we “fall forward” in the autumn, try to wake up a little earlier each day.

Many sleep scientists and sleep medicine physicians argue that the change of time twice a year is an obstacle to healthy sleep. The American Academy of Sleep Medicine advocates for permanent Standard Time as the best solution to improving people’s sleep patterns. Other groups claim permanent Daylight Saving Time is preferable for reasons including facilitation of more commercial and social activity in the evenings year-round. Legislation is currently before Congress on this matter.

Jet Lag

Traveling across time zones can also misalign your circadian rhythm. For example, if you usually go to sleep at 10:00 p.m. Central Standard Time (CST) and you travel to a location in the Pacific Standard Time (PST) zone, your internal clock tells you to go to sleep around 8:00 p.m. And when on PST, you might wake up at 4:00 a.m. rather than your usual 6:00 a.m.

Jet lag affects people differently. Some people only experience jet lag if they have traveled to the other side of the world. For others, even one time zone difference can impact their sleep.

To help minimize or prevent jet lag, begin by gradually shifting your sleep schedule to match your destination’s time a few days prior to your trip. Seeking or avoiding light exposure at strategic times is also important. Apps like Timeshifter® offer personalized trip planning to guide you through this process. Low doses of melatonin (3 mg or less) can help manage jet lag, too.

Using Light to Get in Rhythm

If your bedroom receives limited natural light in the morning, sleep medicine physicians recommend using a lightbox instead. Lightboxes are artificial lights that can be programmed to turn on at the same time every morning for 15-30 minutes. The light emitted mimics sunlight and ideally should deliver at least 10,000 lux at a comfortable sitting distance of 12 to 24 inches from your face. Lightboxes can also help improve mood in patients with seasonal depression.

Regardless of your sensitivity to time changes, it’s important to have a consistent sleep routine of going to bed and waking up at the same time every day, even on weekends. Learn more tips for better sleep with 10 Tips for Better Sleep.

Cooper Clinic offers a comprehensive range of sleep medicine services including office consultations, lab-based studies and in-home testing. Visit the Cooper Clinic Sleep Medicine web page to learn more or call 866.906.2667.

Article written by Sonya L. Merrill, MD, PhD, FACP, Sleep Medicine Physician at Cooper Clinic.