"Six studies on sleep/wake patterns and circadian rhythms were carried out. In summary:
(1) Adrenaline excretion, self-rated activation, and body temperature rhythms
· Persisted during sleep deprivation,
· Resisted adjustment to rotating shift work, but
· Adjusted rather well to permanent night work.
· Adjusted to most schedules and lost its rhythm during sleep deprivation.
· When night sleep was reintroduced the noradrenaline rhythm reappeared while the existing adrenaline rhythm was accentuated.
(2) Exposure to a performance stressor at the trough raised adrenaline to daytime levels. An equally large response was seen at the peak.
(3) Interindividual [occurring between two and four individuals] day-to-day consistency of 3 and 24 hour levels was high for both catecholamines [neurotransmitters that activate--examples are dopamine, epinephrine and norepinephrine]. Intraindividual [being or occurring within the individual] consistency of the 24-hour pattern was high for adrenaline but low for noradrenaline. Cosine estimates of adrenaline phase showed a considerable intraindividual consistency while interindividual consistency was poor. Noradrenaline had poor cosine fit.
(4) Sleep deprivation did not change catecholamine excretion either during the vigil or during recovery sleep.
(5) It was concluded that adrenaline excretion, rated alertness, and body temperature exhibited self-sustained circadian rhythms which made adjustment to new sleep/wake patterns very difficult, and that the noradrenaline excretion rhythm depended on exogenous [outside the body] factors."
Acta Physiol Scand Suppl.: Altered sleep/wake patterns and circadian rhythms. Laboratory and field studies of sympathoadrenomedullary and related variables.