1. L IGHT ON HEALTH Markku Koski

2. C ONTENT OF PRESENTATION Light on health Biological effects of light Seasonal Affective Disorder Bright light therapy Dawn simulation

3. C HARACTERS 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

4. L IGHT AND H EALTH 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

5. B IOLOGICAL 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

6. B IOLOGICAL EFFECTS OF LIGHT Biological clock External cues / stimulation Light Auditive stimulants Physical exercise Drugs Eating habits Social stimulus temperature

7. S TRUCTURE 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

8. C IRCADIAN 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

9. C IRCADIAN RHYTHMS

10. M ELATONIN Night hormone, secretion on pineal gland Strongest regulator is light Melotonin, CBT, cortisol and sleep-wake cycles are in strong correlation C IRCADIAN RHYTHMS

11. S LEEP - WAKE CYCLE What happens without external cues? What happens without sleep? C IRCADIAN RHYTHMS

12. O THER BIOLOGICAL CYCLES AND CORRELATION BETWEEN THEM

13. B IOLOGICAL 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)

14. L IGHT 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

15. S EASONAL 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%

16. S EASONAL 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

17. S EASONAL 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

18. S UBSYNDROMAL 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

19. B RIGHT 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

20. B RIGHT 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

21. B RIGHT LIGHT BEYOND SAD

22. 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).

23. B RIGHT 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)

24. B RIGHT 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

25. D OCTORAL THESIS BY S AMI L EPPÄMÄKI - T HE 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

26. N EW 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

27. B RIGHT 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)

28. B RIGHT LIGHT AND ELDERLY Sleep-wake cycle is more disturbed amongst elderly Disfunction in circadian system

29. B RIGHT 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

30. D AWN 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

31. D AWN 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

32. D AWN 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

33. S UMMARY 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