TABLE 1.

Short summary of Myth-Understandings surrounding DST, providing short explanations and references.

Myth-Understandings	Explanation	References
Summer Time	The colloquial term is used for DST in many countries, but it is misleading since it implies that DST may be responsible for positive attributes of summer (sunny days, warm temperatures, long days) producing falsely positive connotations. Although DST is mostly during summer months, DST is simply an advance of the social clock (we agree to do everything 1 h earlier) and does not “make it summer”	See text for details
Winter Time	This term used for Standard Time is a consequence of calling DST “Summer Time.” It is just as misleading, because Standard Time refers to the social time defined by the time zone and has nothing to do with winter: it does not “make it winter” nor cause short days, cold temperatures or snow	See text for details
Time Change	This term is misleading because DST does not change time but only the local clock, which is used as reference for local (social) time	See text for details
Under DST, “days are longer” or “the sun sets later”	DST does not change day length or the time of sunset; day length changes with season in most parts of the world. During DST, people go to work an hour earlier (relative to sunrise) and come home an hour earlier (relative to sunset)	See text for details
DST is like traveling to the next time zone	It is correct that people can readily adapt to traveling one time zone west or east, but they adapt because their circadian clocks are exposed to the new natural light–dark cycle. DST, however, does NOT change the natural light–dark cycle. DST changes are therefore NOT comparable to traveling to different time zones	See text for details
It is only 1 h	It is true that DST clock-changes are usually 1 h, but the relationship between sunrise and when we start work can change by many weeks. Also, a mismatch of 1 h/day is enough for adverse effects, especially if it lasts chronically for 7 months	See text for details
Negative DST effects in spring are compensated for in autumn	Although the two opposite effects are true epidemiologically, the autumn “relief” cannot rescue the spring victim on an individual level. The spring victims can be only rescued by abolishing the clock advance (DST) Also, the autumn relief indicates the existence of a stressor prior to the clock change, even if that stressor is “merely” chronic sleep deficiency	Manfredini et al., 2018 See text for details
Sun time plays only a minor role for the body clock since it is mainly set by artificial light in modern humans. Environmental temperatures play also a role	The human circadian clock can be set by both sunlight and artificial light, but sunlight is usually up to 1,000-fold more intense and has been shown to affect the clock’s synchronization even in mostly indoor-living people. There is no evidence for clock synchronization by environmental temperature in humans (although sleep times may be affected)	Lucas et al., 2014; Roenneberg et al., 2007b; Buhr et al., 2010; Hadlow et al., 2018
The effects of DST can be neglected compared to those elicited by the use of smart phones	Use of smart phones in the evening can delay the body clock. However, this effect does not compete with the light effects of DST, on the contrary, the two act additively in the same direction, thereby worsening social jetlag (SJL) Evening light delays the clock and morning light advances the clock. Thus, DST decreases circadian clock advances and increases circadian clock delays	Cajochen et al., 2011; Chang et al., 2015; Chinoy et al., 2018; Roenneberg et al., 2003a
Perennial DST does not significantly increase SJL	The reverse is true: the number of people NOT suffering from SJL doubles when switching away from perennial DST to Standard Time (e.g., time zone time) and the number of people suffering from higher levels of SJL are significantly and greatly reduced There have been multiple attempts to implement perennial DST over the past 100 years (e.g., in Russia, the United Kingdom and the United States). In each of these cases, the “experiment” was abandoned after few years	Borisenkov et al., 2017; Ripley, 1974; Uk Time Zone History, 2019; Gray and Jenkins, 2018