Keep a fixed wake-up time, even on weekends

For the most irregular fifth of people, the body clock runs about 2.5 hours later than for the most regular fifth. That is like living with jet lag all the time. Students with more regular schedules also get better grades.

Cost

No money. On weekends you have to sleep in less; that takes a little willpower.

Benefit

61 university students kept records for 30 days. The least regular fifth had a body clock (circadian rhythm) about 2.5 hours later than the most regular fifth. Specifically, the time melatonin began to rise was 00:08 versus 21:32. The stretch when they felt sleepiest was also about 1.8 hours later. The more regular the schedule, the better academic performance (correlation coefficient r = 0.37).

Notes

This is the only study; the sample is small and there was no grouped control. Researchers used a model to estimate that clock differences mainly come from different daily light exposure. They suggest trying light to adjust, but did not run a trial. So besides a fixed wake-up time, getting outdoors for daylight is an inference from their estimate. How to catch up after an occasional late night is in Section 2, Item 38 (after staying up late, catch up the next night): go to bed earlier that night, do not sleep until noon the next day.

Sources · 1

1. Phillips et al. (2017). Irregular sleep/wake patterns are associated with poorer academic performance and delayed circadian and sleep/wake timing. Scientific Reports. doi.org/10.1038/s41598-017-03171-4