Typical sleep EEG changes as well as a pronounced hypercortisolism, characteristics, which have been described earlier, are missing in our populations.
In addition, there was no evidence of sleepiness on the PVT when it was run multiple times in a subset of these subjects compared to subjects with more typical sleep times (7-8 hours/night) (data not shown).
However, in our previous studies, the association between objective sleep duration and hypercortisolemia was based on a four consecutive night sleep laboratory protocol, which should better represent the typical sleep profile of the subjects (6, 7).
Half the participants maintained their typical sleep routine.
So a report in Nature a year ago raised eyebrows: killer-whale and bottlenose-dolphin neonates and their mothers showed little or no typical sleep behaviour for the first postpartum month, remaining mobile for 24 hours a day.
This typical sleep regime of students is usually referred to as the "night owl" schedule of sleep (the term is derived from the principally nocturnal habits of the owl).
They may do so by setting an example (for instance, boasting about sleeping only four hours or sending work e-mails at 3 am), or they may directly shape employees' habits by encouraging people to work during typical sleep hours (perhaps criticizing subordinates for not responding to those 3 am e-mails, or praising individuals who regularly work late into the night).
When the researchers correlated typical sleep durations with the cognitive test results, they found that, regardless of age, participants sleeping seven to eight hours per night performed best, on average, especially on tests of reasoning and verbal ability; short-term memory was not affected by sleep duration.
Data regarding typical sleep times on workdays and free days during the previous month were collected and analysed.
Typical sleep cycles begin around 11 p.m. for teenagers and continue through 8 a.m.
