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How to Reset Your Body Clock: Understanding Circadian Cycles

How to Reset Your Body Clock: Understanding Circadian Cycles

Your body’s sleep-wake cycle is governed by a 24hr internal body clock — also known as your circadian cycle or rhythm. In today’s world, everything from shift work and jetlag to stress and diet can throw this ‘master clock’  out of sync, causing a number of internal problems.

Fortunately, with the necessary changes to your surrounding environment and lifestyle, you can easily recalibrate your circadian rhythm. Here, we’ll outline simple ways to reset your body clock and improve your overall sleep hygiene.

How does your circadian rhythm regulate sleep?

Circadian rhythms are your 24-hour body clock. A cluster of approximately 20,000 nerve cells in your hypothalamus called the suprachiasmatic nucleus (SCN) plays an important role in sleep-wake regulation.
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When sunlight enters the eyes, the SCN interprets this as daylight, which triggers the release of cortisol — one hormone responsible for waking us up. When light diminishes and dissipates entirely, such as at night, the SCN recognises this as a time to sleep. In response, the brain secretes melatonin, the hormone responsible for sleep.

What throws circadian rhythms out of sync?

Your circadian rhythm functions best with regular sleeping habits, such as going to bed and waking up at the same time every day. However, modern life and technology can often disrupt the routine that our internal body clock thrives on.

Travelling is a great example. When you traverse time zones, out-of-synch bedtimes and light cues confuse your internal clock, which is why we often experience jet-lag. But you don’t have to travel for your circadian rhythm to become out of sync. Sleeping outside of the traditional hours — if you work night-shifts, for instance — can have a similarly unsettling impact.

Electronic devices can disrupt your internal body clock, too. Phones, tablets, laptops, and sources of artificial light emit blue light, which tricks your brain into thinking it’s daytime and inhibits the release of your sleep facilitating hormone, melatonin.

How can I reset my circadian rhythm?

Embrace morning sunlight

Prioritising sleep should start as soon as you wake up. Flooding your brain with natural daylight in the morning instructs your brain to stop producing melatonin and start producing cortisol. Morning sun helps to recalibrate the body’s intrinsic circadian clock, it helps you feel alert during the day and tired at night. One study on office workers found that those who were exposed to more light during morning hours (between 8 am and noon) fell asleep quicker at night.i

Top tips for getting morning light:

  • Avoid wearing sunglasses in the morning

  • Have your morning cup of coffee or tea in the garden

  • Plan a trip in nature — the natural sunrise and sunset can help to recalibrate your internal body clock

Avoid caffeine after midday

Caffeine is widely touted for its energising and invigorating properties, namely because it blocks adenosine — one neurotransmitter that promotes sleep.ii The problem is, caffeine can significantly interfere with your circadian rhythm if consumed too late in the day. This is because it can take around 6-7 hours for its effects to wear off.  One study found that drinking coffee 6 hours before bedtime can have disruptive effects on sleep.iii So, if you enjoy coffee, make you sure you drink it before midday.

Top tips to reduce your caffeine intake after noon:

  • Curb your sugar intake, as this will reduce the likelihood of you craving a caffeine beverage in the afternoon

  • Drink chamomile tea in the evening — a great caffeine replacement that also promotes relaxation before bed

Manage stress throughout the day

There is robust evidence to suggest that stress can put your circadian rhythm out of sync.iv High amounts of stress — especially in the evening — can increase your cortisol levels, which function in reverse to your sleep hormone melatonin.

To keep your hormones healthy and balanced, incorporate plenty of relaxation-based activities into your day. Meditation, yoga, deep-breathing, journaling, running, gardening, and dancing can be helpful strategies to tackle daily stressors. Everyone has a unique way of dealing with stress. Find what strategy works for you and stick to it.  

Top tips for managing stress before bed:

Avoid blue light at night

As we’ve discovered, artificial blue light emitted from phone, tablet, and laptop screens can disrupt your internal body clock by tricking the brain into thinking it’s daytime and inhibiting the release of melatonin. As a result, late-night screen use has been found to keep you more alert and energised, making it harder to fall asleep.v

Top tips for reducing the impact of blue light:

  • Turn all e-devices onto ‘night-mode’ and install blue-light blocking software

  • Invest in a pair of blue-blocking amber glasses if evening screen use is unavoidable

  • Refrain from using technology in the 90-minute window before bed

  • Avoid strong, artificial lights in the evening. Try candles or softer lamps instead

To learn more about the reducing the impact of blue light, click here.
We understand that modern life can often skew our internal body clock, but these simple steps should help you recalibrate your circadian cycle and set you on the path to restful sleep. You can discover even more articles on how to improve your sleep routine on our sleep hub.


  1. , et al. The impact of daytime light exposures on sleep and mood in office workers. Sleep Health. 3(3), 204-215.

  2. Coffee Is More Than Caffeine. Journal of Caffeine and Adenosine Research. 8(3), 83-85.

  3. , , et al. Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed. Journal of Clinical Sleep Medicine.

  4. , , et al. Interaction between circadian rhythms and stress. Neurobiology of stress. 6, 57–67.

  5. , & Systematic review of light exposure impact on human circadian rhythm. Chronobiology International. 36(2), 151-170.


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Our Author - Olivia Salter


Olivia Salter has always been an avid health nut. After graduating from the University of Bristol, she began working for a nutritional consultancy where she discovered her passion for all things wellness-related. There, she executed much of the company’s content marketing strategy and found her niche in health writing, publishing articles in Women’s Health, Mind Body Green, Thrive and Psychologies.

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