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. Noradrenaline 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 day-to-day consistency of 3 and 24 hour  levels was high for both catecholamines. Intraindividual 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 selfsustained  circadian rhythms which made adjustment to new sleep/  wake patterns very difficult, and that the noradrenahne excretion  rhythm depended on exogenous factors.