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Diurnal mood variation or morning depression is a prominent [1] depression symptom characterized by gradual mood improvement through the day, reaching its peak sometime after twilight. While the main form of diurnal mood variation presents itself as described, a reversed form, with a worsening of mood towards the evening, also exists. [ 2 ]
Morning types had lower pain sensitivity throughout a day than evening types, but the two chronotype groups did not differ in the shape of diurnal variations in pain. [29] There are some differences between chronotypes in sexual activity, with evening chronotypes preferring later hours for sex as compared to other chronotypes.
People with MDD sometimes show diurnal and seasonal variation of symptom severity, even in non-seasonal depression. Diurnal mood improvement was associated with activity of dorsal neural networks. Increased mean core temperature was also observed. One hypothesis proposed that depression was a result of a phase shift. [30]
According to a study published in 1996: Ultradian mood states in bipolar disorder cycle much faster than rapid cycling; the latter is defined as four or more mood episodes in one year, sometimes occurring within a few weeks. Ultradian mood cycling is characterized by cycles shorter than 24 hours. [6]
And also positive diurnal variation mood (bad mood in the morning, good mood in the evening), [73] sensitivity to negative stimulation and mixed symptoms in some people, etc. [74] [75] Mood swings in post-traumatic stress disorder (PTSD): Mood changes erratically [76] with episodic mood swings rising in the period of recovery process.
In diurnal (day-active) species, exposure to light soon after wakening advances the circadian rhythm, whereas exposure before sleeping delays the rhythm. [11] [12] [8] An advance means that the individual will tend to wake up earlier on the following day(s). A delay, caused by light exposure before sleeping, means that the individual will tend ...
Seasonal mood variations are believed to be related to light. An argument for this view is the effectiveness of bright-light therapy. [24] SAD is measurably present at latitudes in the Arctic region, such as northern Finland (64°00′N), where the rate of SAD is 9.5%. [25] Cloud cover may contribute to the negative effects of SAD. [26]
Chronobiology studies variations of the timing and duration of biological activity in living organisms which occur for many essential biological processes. These occur (a) in animals (eating, sleeping, mating, hibernating, migration, cellular regeneration, etc.), (b) in plants (leaf movements, photosynthetic reactions, etc.), and in microbial ...