Most of us are familiar with our own body clock. Given the opportunity of an extra hour in bed and we still wake up at the same time. Or, the party is still in full swing and we can barely stay awake.
The ‘body clock’ is the result of the Circadian Rhythm, which is the cycle of night and day in a 24 hour period. The circadian rhythm also affects body temperature, blood pressure, digestive secretions and hormone production.
It is also found in other organisms and is mainly controlled by temperature and light. Bird migration is an example of how changes in temperature and length of day influence behaviour.
Circadian rhythm is controlled by the hypothalamus in the brain. This is near to the optic nerve, explaining why light is so influential in sleep. Sleep is controlled by neurotransmitters, which act on nerves in the brainstem and the spinal cord.
The cycle of sleep and being awake in humans is dependant on light and temperature. Any changes can affect the cycle and external factors such as alarms, changes in mealtimes, work or other demands can all take their toll…
Body Clock Problems
Disruptions in Circadian Rhythm can cause Jet Lag, DSPS (Delayed Sleep Phase Syndrome), which creates a need to sleep longer and ASPS (Advanced Sleep Phase Syndrome) the opposite causing early sleeping and waking. As a teenager adjusts to their circadian rhythm they start to sleep and wake later. Eventually they adjust to their adult sleep pattern. DSPS sufferers continue or develop this pattern and will exhibit a preference for going to sleep late and waking later than normal. If they need to wake early they will be ‘drowsy’ for several hours and suffer from loss of sleep. They often fall asleep, sleep and wake as normal but will find it difficult to function outside their ‘preferred’ sleep pattern.
Night shifts can affect workers who find it difficult to readjust to normal night sleeping. Usually those affected are able to adjust after two weeks but for some, the sleep disruption continues for longer.
Jet lag is usually a temporary problem and after a few days or a week the body clock adjusts back to its normal rhythm. Usually the larger the time difference the longer it takes to adjust. Some individuals find these disruptions cause them little problem while others find it difficult to adjust.
ASPS are more or less the direct opposite to DSPS. Sufferers need to have an early night and will be bright and chirpy in the early morning. Some find it difficult to get any sleep after 3 or 4 am.
This condition is quite common in the older adult. They will often make up for this early waking by feeling sleepy and taking a nap in the afternoon.
Although light is the major influence on when we sleep, other influences affect our sleep pattern. If we were all allowed to sleep when we felt the need society would find it almost impossible to function. Work, education and relationships require constant adaptation of our circadian rhythm.
Normally we are able to cope with disruptions such as a foreign holiday or growing up, but for some the problem persists and adjustment is harder. This may suggest the existence of a Circadian Disorder.
Often a gradual move back to normal sleeping times can be achieved by moving bed and waking times, earlier or later, depending on the disorder. By doing this slowly over a period of weeks the body clock adjusts and normal waking and sleeping may be achieved.
Melatonin is produced in the pineal gland in the brain. It is produced during the night and ceases as daylight approaches. It affects our body clock throughout our lives and melatonin supplements are used to help those who suffer from problems with sleep.
Melatonin is only available on prescription in this country.
Bright Light Therapy has also been used to help body clock disorders. Bright light affects the production of melatonin and can be used at different times of day to alter patterns of sleeping and waking.
Getting in touch with your body clock will help to identify your normal ‘rhythm’. When this is affected by life events, such as work and travel, re-establishing a regular routine is often enough to get your sleeping patterns back to normal.