Each of us has an internal body clock, and we live in a rhythmically changing 24-hour cycle of light and dark. Every organ in our body naturally knows when it’s time to work hard and when it’s time to take a break. These are known as circadian rhythms.
‘It’s pointless running your body at top speed all the time if you don’t need it. In fact, it’s impossible,’ says Russell Foster, a molecular neuroscientist at Imperial College, London, and co-author of Rhythms Of Life. ‘Instead, you use what you need, when you need it. It’s a wonderful conservation mechanism.’
If we’re not living in tune with our body clocks, says Foster, then our health and wellbeing may be compromised. And it doesn’t take much for us to be out of synch. Shift work, long-haul travel, pregnancy, a change in routine or stress can all disrupt our body’s natural rhythms.
Some of the most basic concepts in Traditional Chinese medicine are inextricably linked with time. Yin and yang, for example, are related to day and night, while the 12 meridians along which energy travels through the body are linked with 12 two-hour periods and certain organs.
‘Traditional Chinese medicine recognises that each organ has a time when it is at its peak and, conversely, when it is at its weakest. For example, the liver is strongest between 1am and 3am, and weakest between 1pm and 3pm,’ says Henry McGrath from The College Of Naturopathic Medicine and author of Traditional Chinese Medicine Approaches To Cancer. ‘The Chinese clock is used mostly to help diagnose which organ is out of balance. If someone feels tired during the kidney hours (between 5pm and 7pm), then that would point to kidney imbalance.’
Western medicine is now recognising these fluctuations in the body throughout the day, too. ‘There are daily variations in hormone levels that affect the most basic functions in our body,’ says Foster.
Researchers at the University of California School of Medicine have identified a chemical ‘switch’ in our brain that controls the mechanism that regulates our body clock. They found that if this is impaired in any way, the switch mechanism can be affected, undermining our whole system. They hope that this discovery will lead to new treatments for conditions such as insomnia or depression. This could also explain why certain treatments, such as chemotherapy, seem to be more effective at certain times of day.
In experiments at Northwestern University in the USA, scientists found that the body’s internal biological clock affected the survival of immune cells that were targeted by certain anti-cancer drugs. ‘This is not some vague metabolic difference between day and night,’ says Joseph S Takahashi, senior author of the study. ‘This is a tangible difference in the immune system that influences sensitivity to cancer drugs.’ By understanding our body clock and identifying our body’s natural rhythms, we can unlock the energy we need for the day ahead and sleep better at night.