LIGHT ON HEALTHMarkku Koski

CONTENT OF PRESENTATION

Light on health Biological effects of light Seasonal Affective Disorder Bright light therapy Dawn simulation

CHARACTERS OF LIGHT Intensity Illuminance (lux)

Sunlight 100000 lux Bright light therapy 2500-10000 lux Cloudy day 2000 lux Office 300-500 lux

Colour temperature (Kelvin) Incandecent bulb: 2700 K Bright light therapy: 4000 K Dark blue 17000 K

LIGHT AND HEALTH

Positive effects Mood Vitality Alertess Light on skin

Vitamin D production light therapy

throught the skin

Negative effects Seasonal affective disorder Light at Night

Shift work Disturbance to Sleep-wake cycle

Light and cancer Light at night may lead to breast cancer

blue-light hazard UV radiation to eye --> cell deaths in the

eye

Light on skin skin cancer

Effects throught the eye Effects throught the skin

BIOLOGICAL EFFECTS OF LIGHT

Light is not just for vision any more All non-visual effects of light

Biological clock Surrounding world have external rhythms, where people have to adaptate. Organisms have built internal clock, which can react to external cues

BIOLOGICAL EFFECTS OF LIGHT

Biological clock

External cues / stimulation Light Auditive stimulants Physical exercise Drugs Eating habits Social stimulus temperature

STRUCTURE OF BIOLOGICAL CLOCK Non visual photoreceptor in retina Retinohypothalamic track (RHT) Suprachiasmatic nuclei (SCN)

In hypothalamus Master clock of biological rhythms

Pineal gland Melatonin secretion

CIRCADIAN RHYTHMS Circa dies = day Biological rhythms: cycles

around 24 h Well-known circadian cycles

Sleep-wake cycle Hormonal endocrine secretion

Melatonin, cortisol Blood pressure cycle Body temperature Alertness

Light is the strongest syncroniser

CIRCADIAN RHYTHMS

MELATONIN Night hormone, secretion on pineal gland Strongest regulator is light Melotonin, CBT, cortisol and sleep-wake cycles are in strong correlation

CIRCADIAN RHYTHMS

SLEEP-WAKE CYCLE What happens without external cues? What happens without sleep?

CIRCADIAN RHYTHMS

OTHER BIOLOGICAL CYCLES AND CORRELATION BETWEEN THEM

BIOLOGICAL EFFECTS OF LIGHT

Important dates Light is shown to influence plants 24 h cycle (Bunning

1936) Light on melatonin suppression (Alfred J. Lewy 1980) Light is shown to impact human circadian system

(Czeisler 1981) Light alleviates depressive symptoms (Alfred J. Lewy

1982) Seasonal Affective disorder – discription of the

syndrome was presented (Rosenthal 1984) New light sensitive photoreceptor in human retina

detected (David Berson 2002)

LIGHT CAN AFFECT More alert on night (Cajochen 2000) and daytime (Phipps-Nelson 2003)

More productivity in office environment (Mills 2007)

more alert, less daytime sleepiness, more vitality Cognitive performance (Lehrl 2007)

alerness, speed of information processing

SEASONAL AFFECTIVE DISORDER Depressive symptoms

Lack of energy 96% Sadness 96% Social withdrawal 92% Irritation 86% Daytime tiredness 81%

Seasonal symptoms Prolonged sleep 76% Weight gain 74% Carbohydrate craving 70%

SEASONAL AFFECTIVE DISORDER Prevalence ( Lam - Canadian Consensus Guidelines for the Treatment of SAD 1999 )

U.S and Canada ~ 2 % Europe ~ 1 to 3 % Women to men ration 1,6:1 Incidence seems to grow with latitude

Prevalence in Finland (Saarijärvi 1999)

SAD 12 % Subsyndromal SAD 27,1 % No effect on mood between seasons 10% Women to men 2:1 BMI > 26 to BMI 15-25 ratio 2:1

SEASONAL AFFECTIVE DISORDER Why we have this?

Short light period is the strongest trigger of SAD

Circadian rhytm phase delay Genes

Treatment Bright light therapy 2500 lux Dawn simulation 250 lux Fitness training

In combination with light exposure

SUBSYNDROMAL SAD similar to SAD, but patients don’t fill definition of

major depressive disorder More common (Finland 27%) Symptoms as:

craving to food and carbohydrate, difficult awakening and hypersomnia and exhaustion and daytime sleepiness similar to SAD

BRIGHT LIGHT THERAPY 2500 – 10000 lux 30 min – 2 h per day 4000 Kelvin History of research and treatment to SAD 25 years Best result after awakening Effect mechanism

Synchronize circadian rhythms and sleep-wake cycle

BRIGHT LIGHT THERAPY Applications

SAD Response 60-90 % to alleviating depressive symptoms (Lam RW,

Levitt AJ. 1999. Canadian Consensus Guidelines for the Treatment of Seasonal Affective Disorder)

Subsyndromal SAD Non-seasonal depression

12-35% alleviating depressive symptoms, equal to traditional pharmaceutigal drug (Kripke 1998)

Meta-analysis: “light therapy offers modest though promising antidepressive efficacy” (Tuunainen 2004)

Light therapy: effective adjuvant therapy to antidepressant medication (Even 2007, Martiny 2004)

Jet lag

BRIGHT LIGHT BEYOND SAD

BRIGHT LIGHT BEYOND SAD

• illumination and seasonal changes in mood and behavior are associated with the health-related quality of life (Partonen 2008)

• Seasonal changes in mood and behavior are common in a general population (Partonen 2008).

• Disfunction of biological clock may lead to insomnia and metabolical disturbances (Partonen 2008).

BRIGHT LIGHT BEYOND SADOffice environment• Bright light alleviate sub-SAD symptoms, improve the

mood, vitality, alertness and productivity (Avery 2001)

• Improved vitality and mood people with or without sub-SAD (Partonen 2000)

• Continous exposure to bright light may improve quality of life, because it will improve the vitality (Partonen 2000)

BRIGHT LIGHT THERAPY AND PHYSICAL EXERCISE 4 study by National Public Healt Institute (Leppämäki,

Partonen 1998-2004)• Combination: bigger alleviation to atypical depressive symptoms

and more vitality than exercise alone• Carbohydrate craving, prolonged sleep, weight gain

• Effective combination to improve mood and certain components of health related quality of life on wintertime

Social activity, overall mental heath

• Affect also to ”healthy” people

DOCTORAL THESIS BY SAMI LEPPÄMÄKI - THE EFFECT OF EXERCISE AND LIGHT ON MOOD (2006)

Depressive symptoms alleviate 40-66% and atypical depressive symptoms alleviate 45-88%

Bright light alone is more effective on atypical depressive symptoms than physical exercise alone

Bright light dosing two times a week (with or without exercise) is effective to alleviate atypical depressive symtoms, which is associated to wintertime depression

NEW APPLICATIONS OF BRIGHT LIGHT THERAPY Strong seasonality

Adult with attention-deficit disorder Bulimia

circadian system disorders Bright light and elderly

Alzheimer disease and dementia, Parkinson disease

When medication is unwanted Depression during pregnancy/ postpartum depression

BRIGHT LIGHT AND BULIMIA Bulimia is mainly eating disorder, but atypical depressive symptoms

is prevalent Binge eating problems are strongly depentend on season Morning bright light significantly alleviate bulimia symptoms (Lam

RW, Am J Psychiatry. 1994) Significant alleviating on eating disorders during bright light

treatment (Braun DL, Compr Psychiatry. 1999)

BRIGHT LIGHT AND ELDERLY

Sleep-wake cycle is more disturbed amongst elderly Disfunction in circadian system

BRIGHT LIGHT AND WEIGHT CONTROL Seasonal symptoms

Carbohydrate craving 70% Weight gain 74%

Seasonal affective disorder and metabolic syndrome are strongly related (Partonen 2008)

Obesity, high blood sugar level, high blood pressure

DAWN SIMULATION Research subjects

SAD, sub-SAD hypersomnia, difficult awakening, quality of sleep

and morning-time alertness synchronisation of delayed sleep-wake cycle

Treatment parameters Illuminance 150-300 lux Time 15 min to 60 min

DAWN SIMULATION Effect mechanism

Same as in bright light therapy Synchronisation of circadian cycles Effect size almost same as in bright light therapy on SAD (Golden 2005) Dawn simulation is more user-friendly, because treatment happens on

time when subject is on sleep

DAWN SIMULATION Effect mechanism

Same as in bright light therapy Synchronisation of circadian cycles hypersomnia, difficult awakening, quality of sleep and morning-time

alertness Dawn simulation is more user-friendly, because treatment happens on

time when subject is on sleep

SUMMARY

circadian system is important for your overall health

Bright light is not just for SAD anymore Dawn simulation might be leading light

treatment in the future