The role of the visual system in regulation of melatonin; effects on arousal level and psychological health. Per Nylén

Transkript

1 The role of the visual system in regulation of melatonin; effects on arousal level and psychological health Per Nylén

2 Industrialized socity Electric lighting different from solar radiation Lower intensity Spectral content (more longer wave lengths) Timing Light intensity Too low daytime (minutes outdoors/day) Too high night time (completely dark bedroom?) Disturbed sleep/wake cycle common

3 Melatonin is a sleep inducing hormone

4 Basic mechanism Increased Melatonin

5 Less Melatonin

6 24 hours Dark Ljus Light Dark Melatonin Cortisol Dark Light Dark Hour

7 Year Dark Ljus Light Dark Melatonin Cortisol Dark Light Dark Hour Januari 00 April 06 Juli 12 Oktober 18 December 24

8 Does melatonin regulation belong to visual ergonomics?

9 Visual ergonomics Object related Contrast Readability Reflections Sharpness/blurr User related Visual angle Visual distance Visus Readabillity Light related Glare Flicker Reflections Intensity level

10 Light related visual ergonomics Light and vision are intimately involved No light no vision Bad light bad vision Good light a prerequisite for good vision Conscious effects glare reflections visual flicker Unconscious effects unvisual flicker tiredness

11 Insufficient light conditions Tiredness Annoyed Muscular pain Injury Absenteeism Cancer?

12 Cancer Melatonin decreases risk of breast cancer Suggested mechanism Too high light levels during night (shift work) Decreased melatonin Increased risk of breast cancer

13 Effects of melatonin relevant to visual ergonomics Acute effects of decreased melatonin: Pupil diameter Tiredness Core body temperature Chronic melatonin related effects in some individuals: Mode changes/depression

14 Pathway

15 Retinal photoreceptors Visual photoreceptors Circadian photoreceptors Specialised Ganglion cells Pigment: melanopsin Localisation Mostly in inferior retina Mostly in nasal part? Spectral sensitivity Blue light; approx 470 nm Intensity requirement Higher than pure visual demands

16 Should we deal with light induced alertness?

17 Light induced alertness We are evolutionary developed for daylight intensities. Noon daylight levels are seldom found at work indoors Indoor levels often enough for visual tasks but not for proper alertness (>2000 lux; Savides et al.)

18 Conclusions Light induced alertness

19 We should participate in actions aiming at achieving enough light for both visual tasks and proper alertness

20 Shall we deal with light therapy?

21 Light therapy At seasonal affective disorder regular stay in high illumination levels (supervised by a physician) might provide reduced symptoms at SAD (seasonal affective disorder)

22 Treatment of entire visual field

23 Commercial light therapy products

24 Over simplified model The more light, the more active Only the amount of light matters Factors that are not considered Exposure situation (RAS-aktivering mm) Distribution in visual field Wave lenght Individual needs (depressed only tired) Side effects (mania, hyper-activity)

25 The more light, the more active

26 Sites

27 Your company s best investment (?)

28 Upward directed table luminaire

29 Closed blinds Special tubes Colour rendering index: 89 Colour temp: 4000 Price 35 Osram or Philips Standard tubes Recom. price: Low price stores like IKEA etc:

30 Special design luminaries

31 Fixed light source

32 What s wrong?

33 What s right?

34 Conclusions light therapy

35 We should - not participate in light terapheutic actions - work against all all light therapy products that induces bad visual ergonomics like glare etc

36 Preventive actions? Artificial daylight No such light source today Dynamic lighting? Changing spectral content during the day Light distribution Solar like?

37 Flicker prevention needed?

38 Flicker exposure Pituitary gland interpretation? Is it light? Is it dark? Is it getting lighter? Is it getting darker? Confusion?

39 Light modulation (flicker) Light bulb Light tube, 38 mm older luminare 5-10 % 20 % Light tube, 27mm older luminare Light tube, 27 mm modern luminare (HF) % <1 %

40 Detection study of light tube flicker Wellbeeing 64 % 0 % Light perception 71 % 14 % EEG (alfa rythm) 64 % 21 % Correlation at the three parameters calculated together Hyper sensitive to electricity (n=14) Controls (n=14) 50 % 0 %

41 Provisions of the Swedish National Board of Occupational Safety and Health: Workplace Design (AFS 2000:42) Section 11 Daylight At permanent workplaces, on work premises and in personnel facilities intended for more than temporary frequentation, there shall normally be adequate daylight and the possibility of an outside view.

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43 Arbetsmiljöinspektionen - ärende Sjukhusavdelning under jord Fönsterlösa rum Marginell utblick från en enda plats i korridor Även pausrum under jord

44 .. Arbete i fönsterlösa lokaler Relativ risk Arbete i lokaler med avseende på avstånd från fönster/dagsljus meter

45 Fönsterlöst kontor

46 Minimal utblick

47 Åtgärder från AG 30 minuter förlängd lunch för utomhusvistelse/ en fridag i veckan Arbetsrotation med avdelning ovan jord

48 Ännu en icke-visuella effekt Synergonomi eller elöverskänslighet?

49 Arbetslivsinstitutet Undersökningsrapport 1995:31 Flimmer från lysrör en bidragande orsak till elöverkänslighet Wibom R, Nylén P, Wennberg A.

50 Debuterande och utlösande faktorer hos 32 stycken elöverkänsliga % 29 Debuterande Utlösande Bild skär m Lysrör Sol- och CRT glödlju s Elektrisk u tru stn in g

51 Detektionsstudie av flimmer från lysrör Elöverkänsliga (n=14) Kontroller (n=14) Välbefinnande 64 % 0 % Ljusupplevelse 71 % 14 % EEG (alfa) 64 % 21 % Sammantagna utfallet i de tre parametrarna 50 % 0 %