Daylight Saving Time and Training: Adapt and Train On

On the night of 25 October 2026 the clocks in Austria go back from 03:00 to 02:00 — the night is an hour longer, the dial an hour behind. For your training the hour itself is barely the issue. What matters is what happens to the light: from one day to the next, the evening falls an hour earlier into darkness, while the morning becomes light earlier instead. That is what your body clock has to adjust to — and it does so not by calendar entry, but through light, movement and sleep timing.

What actually happens on the night of the change

The clock jumps back 60 minutes; the body clock does not. The circadian rhythm — governing body temperature, hormone release, digestion and readiness to perform — runs on its own period of slightly more than 24 hours and is re-set from outside every day. The clock change delivers a strong signal for that: the same daily routine suddenly meets completely different light conditions. If you train at 18:30, you now start in daylight and finish in the dark; if you run at 6:30, you start in light instead of dusk during the first week.

There is no need to overdramatise it. One hour is a sixth of what a flight to the US produces. Adjusting to a single hour takes two to four days with a well-ordered daily life, because under good light exposure the body clock can shift by roughly one hour per day. The days after the change are therefore not a performance slump but a question of daily structure: meal times, bedtimes and training times shift relative to the clock, not the capacity itself.

Light is the cue — not the time on the dial

The strongest time cue for the body clock is light on the retina, above all the short-wavelength blue component of daylight. Morning light shifts the rhythm earlier (you get sleepy sooner in the evening), evening light shifts it later (you get sleepy later). That is why the autumn change is not a burden for most athletes but an opportunity: the morning becomes lighter, and anyone who gets light in the morning hours — running, cycling, or simply having breakfast by the window — pulls the rhythm earlier and falls asleep more easily at night.

The flip side concerns evening athletes. After the change, the after-work session in the dark season is almost always a session in darkness. That has nothing to do with performance but with recovery: if daylight is missing entirely during the day, the body clock gets no stable morning signal and the rhythm drifts later — exactly the direction that shortens sleep. If you always train in the evening, deliberately collect light during the day: lunch break outdoors, walking part of your commute, desk by the window. The details on light, darkness and recovery are in Sleep and Endurance Performance.

What the evidence shows — and what it does not

The clock change is a well-studied event, but the findings are asymmetric. For the spring change — an hour of sleep is taken away — the picture is relatively clear: in the days afterwards sleep duration is measurably shorter, the number of cardiovascular events rises slightly, and accident figures on the following morning show a bump. For the autumn change, where an hour is added, the situation is far less conspicuous and in some analyses even mildly favourable: more sleep, less morning tiredness.

For performance: the effect of a one-hour shift is small, on the order of around one percent or less. The circadian performance curve with its afternoon peak shifts along with it, and after two or three days it has arrived in the new rhythm. Practically relevant that is at exactly one point: anyone who places a race or a hard key session in the first 48 hours after the change trains at the wrong point in their own rhythm. Recreational runners should not turn this into a science; competitive athletes should plan for it.

The extra hour belongs to sleep

Every year the same temptation: the night is an hour longer, so an hour of training is available for free. That is the wrong calculation. A large share of ambitious recreational athletes sleep between six and seven hours on weekdays — the extra hour of sleep lands exactly in the range where it does the most. While training performance only rises with the right stimulus, sleep improves recovery directly: growth hormone release, glycogen stores, immune function and how hard the next day feels.

The pragmatic split: if your sleep rhythm is stable and your sleep account is balanced, you can extend the weekend long run by 10 to 15 minutes after the change — no more is needed to use the effect. If you are chronically short on sleep during the week, the hour belongs to sleep, no discussion. With a race on the weekend of the change, however, it pays to clear your sleep debt beforehand rather than trying to rescue it on race night — see also the Race Day Checklist.

Morning or evening trainer: where to put your sessions

For morning runners the autumn change is a free advantage. The 6:30 session falls in dawn instead of night, the safety and comfort gain is substantial, and morning light exposure stabilises the rhythm. If you used to get up at 6:00, you now rise at the same time in more light — one reason to stick with the morning routine in this season instead of writing it off as impossibly early. The same applies to cyclists, who in autumn face the choice between the turbo and the road anyway, see Winter Cycling Training.

For evening trainers it is the other way round. The 18:30 session turns into a night session from one day to the next, and with artificial light, a high heart rate and a late arrival home, falling asleep tends to drift later. The obvious fix is to move the session forward — to 17:30 or 17:00, while it is still light. Where that is impossible, the second rule helps: dim the lights at home after training, cut screen time and keep bedtime stable. It is not the training time that is the problem, but the combination of a late stimulus, bright light and going to bed late.

A concrete plan for the week of the change

• Weekend of the change: Train as normal. Do not artificially extend the night before, but do not stay up extra late either — the hour arrives on its own.
• Sunday and Monday: Get up at your usual time, ideally with light. Sleeping until 10 on the Sunday shifts your rhythm two hours in the wrong direction.
• The following four days: Keep training times stable. The clock time is the beat, not the light. No swinging between very early and very late sessions.
• Bedtime: Move it forward in 15-minute steps across the week if you are clearly falling asleep later than before — not abruptly by a full hour.
• Plan races: No A race in the first four days after the change. Warm up longer, choose your start time deliberately.
• Daylight during the day: At least 30 minutes of daylight, preferably in the morning. With a day spent entirely indoors, adaptation is measurably slower.

Safety: the underestimated side of the autumn change

The genuinely relevant effect of the autumn change is statistically clearer in road safety than in athletic performance: in the first week after the change, the after-work traffic falls in dusk instead of daylight, pedestrians and cyclists are harder to see, and road accident figures show a bump in that period. Anyone running or riding in the dark therefore needs more than a token light.

• Be seen, not just see. Reflective elements on calves and arms move and are recognised far better than a reflective jersey that disappears under a jacket.
• A light with reach. A lamp that illuminates the path — not just one that signals. On the bike that includes a second rear light and, where needed, a high-visibility vest.
• Change the route. For the dark phase, choose a route with continuous bike path, street lighting and no blind crossings, not the same loop as in summer. What belongs to that is in Night Running Safety and, for time in the saddle, in Cycling in the Dark.
• Adapt to the surface. Wet leaves, leaf litter on asphalt and wet cobbles belong to the season. The combination of darkness and slippery leaves is the most common cause of autumn crashes — adjust cadence and speed, not the length of the route.

What else the calendar brings in autumn

The clock change is part of a larger transition lasting two to six weeks: shorter days, cooler temperatures, wet leaves, early darkness. Many athletes respond with a quiet retreat — instead of planning, sessions get pushed, three become two, two become one. That is exactly where you lose the form you built in summer, and the clock change is only the visible date at the start of it.

The countermeasure is unspectacular: set the framework for winter early, before the darkness rebuilds your daily routine. How to carry training volume and intensity into the dark season without losing form is in Autumn Training in Endurance Sport. For the structure of the next season — when base, when threshold, when peak sits — the overview under Marathon training from base to goal race helps; the terms TSB, CTL and ATL, which make the form curve readable in the dark season, are explained in the training glossary.

Common mistakes

• Giving the extra hour to training. An extra hour of sleep gives a ready body more than an extra hour of running.
• Sleeping in on the Sunday of the change. Two hours of extra sleep after the change pushes the rhythm in the wrong direction. Keep the wake-up time constant, not the sleep duration at any price.
• Scheduling a race in the first four days. The start time falls into a rhythm trough — no drama, but no friend to a personal best either.
• Continuing to train late in the evening while wanting to get up early. Late high intensity plus late sleep onset plus an early alarm is the worst combination of the dark season.
• Reducing visibility to "I can see the road". When running, what counts is that you are seen — on moving parts, with reflectors.
• Mistaking artificial light at night for a rhythm cue. For the body clock only bright, blue-rich light counts — that is, daylight.

How Peakora handles the dark season

Peakora plans the season beyond the date: in the autumn phase the amount of intensity drops relative to the racing season, volume is maintained and increasingly placed in daylight sessions. In parallel the recovery monitor assesses form and fatigue via CTL, ATL and TSB — when a short night or several shifted sessions knock the rhythm out of step, that becomes visible in the form curve instead of only showing up as a form hole in spring. And because every session in the plan carries a written rationale, the day after a shortened night is no puzzle either: the engine proposes sensible adjustments instead of quietly deleting a session.

Frequently asked questions