Chronobiology is a field of science that examines periodic (cyclic) phenomena in living organisms and their adaptation to solar and lunar related rhythms.
These cycles are known as biological rhythms.
A biological rhythm is a self-sustaining oscillation of endogenous origin.
period levelAmplitud
ePhase
The circadian rhythm can further be broken down into routine cycles during the day:
Diurnal
Nocturnal
Crepuscular
Social zeitgebe
rs
Zeitgebers
“time giver”
Entrainment
Sleep wake cycle is the master output rhythm of the circadian clock
controls REM sleep and the ratioof NREM/REM sleep.
controls NREM sleep
SCN
MT2
MT1
phase-shifting and entrainmenteffects of melatonin.
Inhibits he electrical activity ofSCN neurons
Melatonin
Retinal Ganglion cells
Suprachiasmatic Nucleus
Ventral Subparaventricular zone of the hypothalamus
Dorsomedial Hypothalamus
VLPO(ventrolateral preoptic
area)
Sleep
LHA
Arousal
Sleep changes as markers for depression
depressed patients show a reduction in the absolutenumber of delta waves during the first NREM
depressed patients show a reduction in decrease in delta activity throughout the night
sleep abnormalities in the first degree relatives of depressed patients suggests that these sleep changes can be viewed as “markers” of depression
patients with decreased REMOL prior to treatment are prone of developing subsequent episodes of depression and experiencing rapid relapses after remission
There are two theoretical ways:
the older the person, the more the
tendency to have a ‘‘morningness
’’
depressed patients reported significantly more ‘‘eveningness’’ than age- and sex-matched controls
morning type might be protective
against depression
whereas ‘‘eveningness’’
might cause increased
vulnerability
‘‘eveningness–morningness’’
dimension
Dawn simulation therapy
Refractory
unipolar
depression
Bipolar depres
sion
Antepartum
depression
Ttt of choic
e
Valproate
Lithium
Agomelatin
e
Melatonin
MT2 recept
or agonist
5 HT2C antagonist
MT1 recepto
r agonist
25 mg/day
P450 syste
m