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Misaligned cycles lead to adverse cardiometabolic consequences in this laboratory study.

We don't feel right when we change our sleep/wake schedule, whether due to shift work, jet lag, daylight savings time, or illness. Humans have daily behavioral cycles (sleep/wake and fasting/eating) and endogenous circadian cycles (e.g., temperature). These researchers examined the metabolic, autonomic, and endocrine effects of disrupting the alignment between these cycles in 10 adults (5 women).

The participants underwent a multiday protocol in an environment free of time cues. Two 24-hour baseline periods with 8-hour sleep opportunities at subjects' regular time were followed by seven 28-hour cycles, with sleep and wake periods scheduled in a 1:2 ratio. Subjects received isocaloric meals every 4 hours in wake periods. Exercise was prohibited.

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