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New research (Journal of Neuroscience, Dec 2006) demonstrating the link between serotonin levels and our ability to appreciate the salt and bitterness of food explains why carbohydrate cravings and weight gain are so closely associated with Seasonal Affective Disorder (SAD).
However, this finding also goes a long way towards explaining the mechanism that links the obesity epidemic with lifestyle changes over the last twenty years.
Classical SAD where clinical depression is actually diagnosed by psychiatric assessment affects 2-5% of the population but over 40% of us suffer sub-syndromal SAD or ‘winter blues’. This typically involves carbohydrate craving, lethargy, lack of energy and depressed mood. The traditional treatment of winter blues is the prescription of SSRIs such as fluoxetine (Prozac).
The cause is actually a crucial lack of bright sunlight first thing in the morning which is necessary to turn off the production of melatonin – the sleep hormone. Melatonin is produced in the pineal gland by the conversion of serotonin. Therefore a lack of morning sunlight is directly responsible for high levels of melatonin and low serotonin resulting in the typical SAD symptoms.
Research by Dan Kripke in California has demonstrated that our 21st Century lifestyle means that most of us are permanently light-deprived and half the population could suffer non-seasonal symptoms similar to SAD even in a Californian summer. A simple lack of bright sunlight could be a key factor in the national epidemics of obesity and depression.
The ‘cure’ is well-known to SAD sufferers and can be achieved with a simple 15 minute dose of bright light therapy on waking. But not just any light! The melatonin mechanism is triggered by light at the key wavelength of 460-470nm and this is exactly what is produced by the revolutionary Light Emitting Diodes (LEDs) in the Litebook elite. Light therapy has been shown to be as effective as fluoxetine (Prozac) in the treatment of seasonal depression with fewer side effects and more rapid onset ( Am J Psych. May 2006)
The latest announcement that obesity in children is linked to a lack of sleep comes as absolutely no surprise to those working with light therapy.
The human body clock is controlled by intense bright white light switching off the production of melatonin at dawn each day. When this mechanism does not work correctly we experience seasonal affective disorder (SAD), winter blues and, increasingly, non-seasonal depression (aka social jetlag). The typical symptoms of these conditions are depressed mood, lack of energy, carbohydrate craving and weight gain. These are exactly the symptoms expressed by teenagers for the following reason:
At puberty there is a fundamental shift in the body clock mechanism resulting in a sleep pattern that means that teenagers and students do not begin melatonin secretion until the early hours, and therefore cannot sleep. They do not naturally want to wake up until noon. All parents are familiar with this patte rn.
By forcing children to wake at 8am to go to school means that their sleep duration and efficiency is compromised. In the US research shows that most teenage accidents occur before noon. Vigilance and accuracy are at naturally low levels in the morning because melatonin levels are still high so their academic work suffers because of an inability to concentrate – for totally natural reasons.
An increasing number of enlightened (sic) parents are encouraging their children to use light therapy as soon as they wake or on the journey to school. The effects are dramatic. 15 – 30 minutes of intense bright white light using The Litebook are enough to turn teenagers into human beings!
Clinical trials into childhood obesity and chronic fatigue in children are already in the planning stage and it is hoped that funding can be found to run a trial on the use of Litebook light therapy in adult weight control. The confirmation that light therapy offers a low cost, simple and drug-free solution to weight gain could revolutionise our approach to the obesity problem.
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