What is Circadian Rhythm?
If you’ve ever noticed that you tend to feel energized and drowsy around the same times every day, you have your circadian rhythm to thank. What is it, exactly? Your circadian rhythm is a 24-hour internal clock that is running in the background of your brain and cycles between sleepiness and alertness at regular intervals.
For most adults, the biggest dip in energy happens in the middle of the night (somewhere between 2:00 am and 4:00 am, when they're usually fast asleep) and just after lunchtime (around 1:00 pm to 3:00 pm, when they tend to crave a post-lunch nap). Those times can be different if you’re naturally a night owl or a morning person. You also won’t feel the dips and rises of your circadian rhythm as strongly if you’re all caught up on sleep. It’s when you’re sleep-deprived that you’ll notice bigger swings of sleepiness and alertness.
A part of your hypothalamus (a portion of your brain) controls your circadian rhythm. That said, outside factors like lightness and darkness can also impact it. When it’s dark at night, your eyes send a signal to the hypothalamus that it’s time to feel tired. Your brain, in turn, sends a signal to your body to release melatonin, which makes your body tired. That’s why your circadian rhythm tends to coincide with the cycle of daytime and nighttime.
Your circadian rhythm works best when you have regular sleep habits, like going to bed at night and waking up in the morning around the same times from day to day (including weekends). When things get in the way, like jet lag, daylight savings time, or a compelling sporting event on TV that keeps you up into the wee hours of the morning, you can disrupt your circadian rhythm, which makes you feel out of sorts and can make it harder to pay attention.
Interestingly, your circadian rhythm will likely change as you get older. And you may not have the same sleep/wake cycle as your partner, child or parents. But the more you pay attention to your body and notice feelings of alertness and drowsiness, and the more time you spend developing good sleep hygiene habits, the better your slumber will be and the better you'll feel.
How can I reset it?
Adjust your bedtime. Try slowly scaling back your bedtime until you are at the desired hour.
Do not nap. Even if you feel tired, napping can interfere with going to sleep at night.
Do not sleep in. Getting up at the same time every day is important in maintaining a functioning sleep schedule.
Be strict about your sleep schedule. Once you have reached a workable bedtime, don’t allow yourself to stray from it. Even one late night can ruin the progress you’ve made.
Avoid night light. According to research from Rush University Medical Centre in Chicago, exposure to evening light shifts your body clock to a later schedule. When possible, avoid bright and outdoor light close to bedtime and keep your surroundings dim at night.
Avoid eating or exercising too close to bedtime. Also watch out for caffeine and nicotine, both of which are stimulants.
Normalize meal times. Once your sleep is back on track, stick to regular breakfast and dinner times to help support consistent circadian rhythms. Eat dinner at least a few hours before bed, and a filling breakfast shortly after waking.
Set the mood. Finally, create a relaxing bedtime routine with a warm bath and relaxing music, for instance. Make sure your bed is comfortable, the room is dark, and the temperature is not too warm.