Saturday, 7 February 2015

Vitamin Sleep - Part 2 (The Circadian Rhythm)

Circadian Rhythm

According to *'The American Heritage Stedman's Medical Dictionary, the circadian rhythm is defined as a daily rhythmic activity cycle which is based on 24-hour intervals. (*taken from HERE)

This cycle is influenced by regular variations in the environment such as the alternation of night and day. 

The circadian rhythms affect the sleeping and waking in animals, the opening and closing of flowers in angiosperms and the tissue growth in fungi. 

So in layman's term, this circadian rhythm which is present in humans and most animals is generated by an internal clock that is synchronized to light-dark cycles and other cues in an organism's environment. It causes one to wake up at the same time every day without the use of an alarm clock! The circadian rhythm also causes the nocturnal to function in the night and the diurnal in the day. 

The Interruption of the Circadian Rhythm

If one's daily schedule changes, it can interrupt the circadian rhythm. An example would be jet lag. The shift in time and light forces the body to change its usual cycle of regular pattern. Another would be working at night-shift. Or constantly being indoors with artificial lights with no exposure to sunlight. 


*The Circadian Rhythm is controlled by a part of the brain called the Suprachiasmatic Nucleus (SCN). This is a group of cells which are in the hypothalamus that respond to light and dark signals. 

Light travels from the optic nerve of the eye to the SCN which then triggers the internal clock that it is time to be awake. This SCN also plays a part in hormones, body temperature and functions that play a role in making us feel sleepy or awake. 

The exposure to daylight triggers the SCN to send signals to raise the body temperature and produces the cortisol hormones. 

The SCN also responds to light by delaying the release of the melatonin. Melatonin plays a part in promoting sleep as it is produced when the eyes signal to the SCN that it is dark. Hence, when there is less light, the SCN tells the brain to produce more melatonin to make you sleepy. (Thus it is a bad idea to watch TV or be in front of computers/tablets/smart phones as they can screw up your signals!)

People who work at the night shift produce less melatonin. Also people who are constantly in offices (with artificial lights) and with no windows, tend not to have a stable circadian rhythm. 

It is good to be exposed to morning sunlight as it helps the circadian rhythm to regulate. 

It is also very important to keep a regular sleep schedule to allow deep and quality sleep. 


Circadian Rhythm Disorders

*The circadian rhythm disorders can be triggered by pregnancy, shift-work, time zone changes, medications, changes in routine where sleeping is concerned, health problems and mental health problems. 

(*taken from HERE)

Common Circadian Rhythm Problems

  1. Jet-Lag - Excessive sleepiness or a decline in daytime awareness due to the change in time zone.
  2. Shift-Work Sleep Disorder - Unable to sleep or have quality sleep due to rotating of shifts or works at night.
  3. Delayed Sleep Phase Syndrome (DSPS) - Only able to fall asleep very late at night and unable to wake up in time for work, school or appointed schedules. 
  4. Advanced Sleep Phase Syndrome (ASPD) - Excessive sleepiness much too soon before bedtime (6pm to 9pm) and waking up earlier than desired (1am to 5am).
  5. Non 24-Hour Sleep Wake Disorder - This affects blind people as the gateway to the CNS is not functioning. As a result, sleep time, quality and problems staying awake persist. 

How To Treat Circadian Rhythm Disorders

  1. Sleep Hygiene Techniques - Practices, habits and environment factors that are important in getting quality sleep. 
  2. Sleep Restriction Therapy - The bed is only for sleeping and nothing else. Thus, time in bed is limited. 
  3. Chronotherapy - A behavioral technique where bedtime is gradually and systematically adjusted until a desired bedtime is achieved. 
  4. Bright Light Therapy - Used to reset a patient's circadian rhythm to a desired pattern.

Circadian Rhythm Trivia

1. The SCN (suprachiasmatic nucleus) contains about 20,000 nerve cells!

2. Even fruit flies, cyanobacteria, algae and fungi (YES! Fungi!) have genes that direct the circadian rhythm.

3. The 'after-lunch-sleepiness-syndrome' is not caused by lunch. It is the body's natural circadian rhythm where our energy levels naturally dip between 1 to 3pm, where 3pm being its lowest.

4. Morning sunlight is the most powerful regulator for our biological clock (circadian rhythm).

5. In order for a biological rhythm to be called circadian, it must fulfill three criteria: The rhythm must persist in constant conditions for a 24-hour period (entrainment), the rhythm can be reset by external stimuli (light and heat) and the rhythm must maintain the circadian rhythm even though temperature changes. 

6. A French scientist by the name of Jean-Jacques d'Ortous de Mairan discovered circadian rhythms in 1729. Click on LINK to read more.

Interesting Articles to Read

Disruption of Circadian Rhythm May Contribute to Inflammatory Disease When Coupled with High Fat & Sugar Diet

Why Circadian Rhythm Affects Your Health

Ideal Work Schedule As Determined By Circadian Rhythms

Key Element in Circadian Clock Speed Discovered

Circadian Clock An Orchestra With Many Conductors

Sleepless in America

1 comment:

  1. We'll I'm screwed...I live where the sun rarely shines most of the year and work indoors as well. I've read, too, if you get up in the middle of the night you should never turn on the lights as that signals the brain to rise and shine and since so many people wake up around 3am due to blood sugar issues, this is a good strategy for getting back to sleep easier.