Circadian Rhythm 101
How to Keep Your Body Clock in Tip-Top Shape
Like millions of Americans, you put your clocks back an hour last weekend, and like many of them, you may be feeling sleepy, listless, stressed and tired. Why? Because the time change has an impact on our Circadian rhythms. These 24-hour cycles – “Circadian” comes from the Latin “circa diem,” which means “around a day” – regulate our sleep-wake schedules, along with other important bodily functions, such as appetite, mood, and even the immune system. These rhythms are heavily dependent on exposure to light, and to maintain optimal health, must be synchronized each day with natural light and darkness cycles to ensure quality, restorative sleep.
When light enters the eyes - even when they’re closed, during sleep – it stimulates a signal in the back of the retina that runs down the optic nerve to the circadian clock in the Suprachiasmatic Nucleus (SCN) of the brain. The SCN triggers other parts of the brain to control hormones, body temperature and other functions that make us feel either sleepy or alert. Jet lag resulting from crossing time zones, working night shifts or simply being a night owl – anything that exposes you to light at odd hours and misaligns your sleep cycle with natural cycles of light and dark – can throw off your circadian rhythms. So can occasional stress and certain medications.
Stable circadian rhythms contribute to overall health and well being, helping to support the digestive and cardiovascular systems and regulate hormone levels and metabolism. Healthy weight and blood sugar levels are also easier to maintain when your sleep-wake cycle is optimized. As scientists have begun to understand the link between our health and our circadian clocks, they have also learned how to keep them in tip-top shape. Here are five tips to keep yours ticking smoothly.
Seek the Sun
Evolutionarily, natural light is the driving force behind our Circadian rhythms. Exposure to natural light, especially early in the day, stimulates the body and the mind and increases energy and alertness. As the day progresses, spending time outside can alleviate afternoon feelings of tiredness because exposure to sunlight will suppress the production of melatonin until you’re ready for bed. This is why, after an overnight flight to Europe or a redeye from Los Angeles to New York, it’s better to go outside for a walk than to immediately hit the sack; exposure to light in your new time zone signals your body that it’s time to be awake.
Exercise during the day supports your circadian clock and makes it easier to fall asleep at night, but time of day matters. Activity in the morning or afternoon advances your body clock, making it easier to fall asleep and wake feeling refreshed the next day. Exercise in the evening delays the body clock, making it harder to fall asleep and causing morning sluggishness.
Avoid Stimulants After Lunchtime
Caffeine, alcohol and nicotine can all prevent you from falling asleep and cause you wake up more often during the night. Caffeine has been shown to delay the release of the sleep hormone melatonin. Nicotine can actually alter the expression of genes that control the natural sleep-wake cycle. But while caffeine and nicotine are stimulants, alcohol is a central nervous system depressant that may give the illusion of relaxation. However, drinking – especially in excess – increases the symptoms of insomnia. It is also believed that alcohol acts directly on the circadian clock to alter circadian rhythms.
Set a Consistent Sleep Schedule
A constantly changing bedtime or morning wake-up time can inhibit your body’s ability to adjust to a stable Circadian rhythm, while sticking to a one-hour bedtime and wake-up window helps you to feel refreshed, energetic and ready for your day. Of course, there will be late nights and early mornings, but controlling the nights and mornings you can control and getting back to your sleep-wake routine after disturbances to your sleep will help you get the rest you need. Additionally, keep naps short and early in the afternoon: Late and long naps can push back your bedtime and throw your sleep schedule off-kilter.
Embrace the Dark
Indoor lighting allows us to stay awake long past sunset, but constant exposure to artificial light has moved us farther and farther away from our natural sleep patterns. Experts advise dimming the lights and putting down electronic devices three hours before bedtime. Try something analog for entertainment, like reading, drawing, board games or meditating.
The darker your bedroom, the better, as darkness sends a signal that it’s time to sleep in the same way light sends a signal to wake up. Close the blinds or wear an eye mask. Turn your alarm clock so the light from the numbers faces away from you, or flip your cell phone over so the screen won’t light up and disturb your sleep. Or better yet, turn it off. If you or your child need a nightlight to navigate to the bathroom in the middle of the night, try one with a red bulb; red has a longer wavelength and is less disruptive to sleep.