SleepChart
SleepChart is a sleep logging application that makes it possible to optimize sleep. Version 1.0 is freeware and standalone. Version 2.0 is integrated with SuperMemo for Windows. Version 2.0 helps you optimize learning in reference to sleep and optimize sleep using your learning data.
See more:
- SleepChart version 1.0: free download (download)
- SleepChart version 2.0 is integrated with SuperMemo for Windows
- Charting sleep
- Excellent user guide for SleepChart at supermemo.wiki
This glossary entry is used to explain "Good sleep, good learning, good life" (2017) by Piotr Wozniak
Figure: Changes in alertness in the course of a day (i.e. in the course of a 24-hour circadian cycle). Alertness is expressed here as learning performance. Sleep data come from a SleepChart log. Learning data come from SuperMemo. Best learning performance occurs early in the morning. There is a second peak of good performance in the evening (13-17 hours from waking). Sleepiness is the opposite of alertness. Optimum time for a siesta nap occurs in the 8th hour since waking. The two dips in alertness correspond with optimum times for sleep in a biphasic sleep cycle. Horizontal axis corresponds with the circadian phase, i.e. the number of hours since awakening in the subjective morning. 0 on the horizontal axis corresponds with circadian Phase 0, i.e. the optimum/natural waking time. Vertical axis corresponds with the average recall in learning based on spaced repetition. Blue dots express recall at a given circadian phase/time (in percent). Thick blue line is the approximation of the circadian alertness derived from a two-process model of sleep regulation (inspired by Alexander Borbely). Learning performance (thinner line) provides a good match to circadian alertness (thicker line).
Figure: Optimizing the timing of brainwork with respect to the circadian cycle. This graph was generated with the help of SleepChart on the basis of 3-year-long daily measurements of a free-running sleep rhythm. The horizontal axis expresses the number of hours from awakening (note that the free-running sleep cycle period may be longer than 24 hours). Light blue dots are actual sleep episode measurements with timing on the horizontal, and the length on the left vertical axis. Homeostatic sleepiness can roughly be expressed as the ability to initiate sleep. Percent of the initiated sleep episodes is painted as a thick blue line (right-side calibrations of the vertical axis). Adenosine-related homeostatic sleep propensity increases in proportion to mental effort and can be partially cleared by caffeine, stress, etc. Circadian sleepiness can roughly be expressed as the ability to maintain sleep. Average length of the initiated sleep episodes is painted as a thick red line (left-side calibrations of the vertical axis). Mid-day slump in alertness is also circadian, but is biologically different and results in short sleep that does not register as a red peak. Sleep maintenance circadian component correlates (1) negatively with core body temperature, ACTH, cortisol, catecholamines, and (2) positively with: melatonin and REM sleep propensity. Optimum timing of brainwork requires both (1) low homeostatic sleepiness, and (2) low circadian sleepiness. There are two high quality alertness blocks during the day: the first after the awakening, and the second after the siesta. Both blocks are marked as yellow bands below the graph. For best learning, and for best creativity, use these two yellow blocks of time. Caffeine can only be used to enhance alertness early in the optimum brainwork window (brown). Later use will affect sleep (caffeine half-life is about six hours). Optimum timing of exercise is not marked as it may vary depending on the optimum timing of zeitgebers (e.g. early morning for DSPS people and evening for ASPS people). For more details see: Biphasic nature of human sleep
Figure: Biphasic circadian cyle of learning performance in a teenage non-napper. Habitual napping amplifies the clarity of the circadian cycle. Learning performance is an excellent illustration of the biphasic cycle. In habitual napper, a deep valley in alertness emerges around hours 8-12. However, the same valley can be observed in non-nappers who find their own strategies in coping with the dip (e.g. using it for exercise or socializing). Unlike nappers, the second half of the day shows weaker performance even if it goes against subjective feelings of the student. Blue dots represent recall in SuperMemo. Their size reflects the availability of data and shows that non-nappers instinctively or habitually reduce their learning load around the 8th hour of the day. The presented graph represents a remarkable number of 45,140 repetitions, and 9,145 sleep episodes (5,461 after consolidation)