This paper by Nikitopoulou and Crammer was published in the BMJ in 1976. This is a very nice, simple study involving ‘six manic-depressive patients‘. The body temperature was measured with ‘clinical thermometers, which were left for at least three minutes in the axilla‘. The researchers examined changes in body temperature in the patients, who experienced a spontaneous switch from one state to another. Thus the patients acted as their own controls. The researchers analysed the diurnal variation in body temperature in both manic and depressive phases.
What they found was very interesting. The normal course of temperature change is for some stability in the morning with a gradual increase in the afternoon. This was observed in the manic phase. However in the depressed phase, ‘the temperature dropped when the patient got up‘. The researchers therefore distinguish between the circadian rhythm for temperature in depression and mania.
They interpret this in terms of two circadian rhythms in mammals, one entrained to dawn and the other to dusk. The researchers also comment earlier in the paper on the role of Sertraline and Noradrenaline in the circadian rhythms. The researchers hypothesise that there is a desynchronisation of these two circadian rhythms which may result in some of the experiences in Depression.
Looking at the previous paper covered in this post, it is interesting to speculate on whether a high maximum environmental temperature would be associated with a synchronisation of the two circadian rhythms (bearing in mind that the previous paper showed some evidence for a transition from depressed to elevated mood with high maximum environmental temperature). If this were the case, it would imply the converse – that a lower maximum environmental temperature would increase the probability of a desynchronisation of the circadian rhythms.
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