We studied the effect of the switch from daylight saving time to winter time on punctuality for medical appointments, thus allowing us to investigate the role of dynamic and analytic modes of time management in time‐based prospective memory tasks. Insofar as some authors assume that the dynamic mode of time management is based on rhythms, we hypothesised that the switch from daylight saving time would cause more disturbances when participants' everyday activity had a weak temporal structure. Results showed that after the switch, participants arrived early for their appointments, but this earliness was not higher for participants whose everyday activity had a low temporal structure than for participants with highly structured everyday activity. Nevertheless, compared to the time they planned to arrive, participants with low regularity of activity arrived earlier after the switch, suggesting that their temporal reference would the time fixed by themselves, rather than the appointment time. Copyright © 2016 John Wiley & Sons, Ltd.