I live in Massachusetts, where a state committee responded favorably to a bill (and referred it to the committee on Senate Rules, earlier this year) that aimed to end the twice-a-year clock change and move the state to permanent Atlantic Standard Time (effectively year-round daylight savings time). For many people, the most noticeable consequence of the clocks changing (this year it’s November the 1st, 2026) is that it suddenly becomes dark much earlier in the evening. A journey home from work that took place in daylight on the Friday before may be undertaken largely in darkness the following week. From a criminological perspective, this abrupt change provides an interesting opportunity to examine the relationship between darkness and crime. It might seem reasonable to assume that crime increases when the clocks go back because offenders prefer darkness. However, the relationship is somewhat more complicated. There is little evidence to suggest that the overall crime rate increases when Daylight Saving Time ends. Different offenses have different seasonal patterns and are influenced by factors such as people's daily routines, school/work schedules, holidays, alcohol consumption, etc., and the amount of time people spend outside the home. There is, however, evidence that changes in daylight can affect particular offenses, especially street robbery and assault.

One study of this phenomenon was conducted by economists Jennifer Doleac and Nicholas Sanders (2015), who examined the changes created by Daylight Saving Time as a type of “natural experiment”, concerning darkness and crime. Normally, it is difficult to separate the effects of darkness from all the other variables associated with different seasons e.g., December isn't just darker than June, it is also colder, people's activities are different, schools and universities operate differently, and Christmas and other holidays alter shopping, travel and social behavior. Their research was able to focus on the effect of “darkness” on crime, as people's schedules remained broadly similar, before and after the clock change. However, the relationship between those schedules and daylight suddenly changes. Someone who leaves work at 5:00 p.m. may leave at essentially the same time before and after the clocks change, but their environmental conditions are different i.e., they are now leaving in darkness. Doleac and Sanders’ study found evidence that additional evening daylight was associated with reductions in robbery. Their analysis estimated that the shift into Daylight Savings Time produced approximately a 7 percent reduction in robbery overall, with considerably larger effects during the period around sunset. Conversely, when Daylight Saving Time ended in Autumn and evening darkness arrived earlier, robbery increased. The researchers' results therefore suggest that ambient light can influence opportunities for particular crimes.

This finding makes sense when viewed through the lens of Routine Activity Theory (RAT). Routine Activity Theory (Felson & Cohen) makes the case that a crime occurs when three elements converge in time and space i.e., there has to be a motivated offender, a suitable target and the absence of capable guardianship (this could be the presence of security, whether cameras or a person etc., or even just the presence of someone who would witness the offenses taking place. The theory directs the attention away from asking “why” someone commits a crime and toward asking why a particular criminal opportunity occurs at a particular place and time. The theory focuses on the “criminal incident” and ignores the criminality/personality and motivation of the offender. The change in DST provides an opportunity to see the effect of darkness on an unchanged routine. A person who finishes work at 5:00 p.m. and walks ten minutes from their workplace to a transit station/stop, isn’t likely to change this routine immediately when the clocks go back. They’ll leave the same building, walk along the same streets, carry the same phone and bag, and catch the same train. What changes is the environment through which they move e.g., before the clock change, much of that journey may take place in daylight. Afterwards, it may occur in darkness.

Darkness can alter several elements of a criminal opportunity e.g., an offender may believe that they are less likely to be identified, potential witnesses may have greater difficulty observing what is happening, and surveillance cameras may produce less useful images, depending upon their capabilities and lighting conditions etc. A potential victim may also have greater difficulty seeing someone approaching or recognizing environmental cues that would otherwise attract their attention. This doesn’t mean that darkness somehow creates more criminals, it simply creates more offending opportunities. Also, the person contemplating a robbery at 5:45 p.m. doesn’t suddenly become more criminally motivated because the sun has gone down. Rather, darkness may alter their assessment of the opportunities that are available and favourable to them. Crime is frequently discussed as though environments are either "safe" or "dangerous" e.g., “bad parts” of a town/city versus safe/good ones.  From a personal safety/self-protection perspective a more useful/constructive approach is to think about how environmental conditions change the probability of particular events. Darkness represents just one variable amongst many, e.g., the number of people present, the availability of escape routes, natural surveillance, guardianship and the attractiveness of potential targets all influence an offender's decision-making.

There is also evidence suggesting that the relationship between daylight and crime differs significantly according to offense type. A study examining Daylight Saving Time changes across eleven densely populated U.S. cities (Mitre-Becerril, 2026) found that an additional hour of daylight was associated with a substantial reduction in robberies around sunset. However, the researchers also found that this corresponded with an increase in aggravated assaults. It is always worth reminding ourselves that different crimes require different types of opportunity. Robbery is largely an instrumental offense, where an offender looking to take something from a target, may benefit from the reduced visibility that darkness affords them, and so therefore may offend less during daylight hours. Assaults are often the result of interpersonal encounters. Longer daylight hours may encourage people to remain outside longer, socialize, travel, drink or otherwise interact with other people. Increasing the number and duration of social encounters can potentially create additional opportunities for disputes and assaults even while making robbery less attractive. So, it is not that daylight prevents crime and darkness promotes it, but rather environmental changes can suppress one type of opportunity whilst promoting another.