Light on health

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Light on health

• Markku Koski

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Content of presentation

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

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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

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Light and Health

• Effects throught the eye
• Effects throught the skin

• 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 --gt cell deaths in the eye
• Light on skin
• skin cancer

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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

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Biological effects of light

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

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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

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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

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Circadian rhythms
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Melatonin
Circadian rhythms

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

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Sleep-wake cycle
Circadian rhythms

• What happens without external cues?
• What happens without sleep?

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Other biological cycles and correlation between
them
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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)

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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

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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

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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 1,61
• 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 21
• BMI gt 26 to BMI 15-25 ratio 21

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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

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Subsyndromal SAD

• similar to SAD, but patients dont 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

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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

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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

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Bright light beyond SAD
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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).

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Bright light beyond SAD

• Office 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)

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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

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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

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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

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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)

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Bright light and elderly

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

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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

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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

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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

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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

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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