Impact of extreme physical exercise (28 consecutive marathons) on sleep time and structure, 2025, Buela-Casal et al

[forestglip]

Impact of extreme physical exercise (28 consecutive marathons) on sleep time and structure

Gualberto Buela-Casal, Noelia Ruiz-Herrera, Alejandro Guillén-Riquelme, Carlos Zamarrón, Francisco Gude-Sampedro

Objective
It is known that physical exercise influences sleep, however, the effect in extreme sporting conditions has been less studied. We analyzed the sleep quality and duration of an athlete who ran 28 consecutive marathons (one per day).

Methods
We evaluated with three polysomnography recordings to explore the sleep-dependent recovery process: Post-marathons, partial recovery, and baseline.

Results
The participant reported a low sleep quality during the challenge, along with short sleep time, several awakenings, and daytime sleepiness. We observed differences in sleep duration, quality, and distribution in all variables evaluated through polysomnography. From baseline to the final condition after the physical test, we observed a progressive decrease in sleep time and sleep efficiency. In addition, we observed an increase in sleep onset and REM sleep latencies, a 45.8 % increase in slow wave sleep, which affects the complete sleep structure after physical exertion. REM decreased by up to 14.4 % because of intense and continuous physical exercise, and with respect to SWS (38.5 %) this represents an increase in SWS of 267 % with respect to REM.

Conclusion
sleep is affected by high-intensity physical exercise and is modulated by the recovery process. The results of this study highlight the importance of SWS in the recovery from physical fatigue due to the effect of extreme physical exercise, which is demonstrated by the enormous increase in SWS that accounts for almost 40 % of the Total Sleep Time, surpassing even the stage 2 percentage. It is also shown that REM sleep has no role in the recovery from physical fatigue, as it is in fact considerably decreased by the effect of extreme physical exercise. Previous studies had not reported results with these magnitudes.

Link | PDF (International Journal of Clinical and Health Psychology) [Open Access]

 

[forestglip]

Maybe 28 consecutive marathons (!) is what it takes for a healthy person to experience PEM.

 

[Utsikt]

I’ve walked less than a single marathon in total the last year. But at least I can walk!

It is also shown that REM sleep has no role in the recovery from physical fatigue, as it is in fact considerably decreased by the effect of extreme physical exercise.

I don’t understand this. How have they showed that REM doesn’t play a role in recovery from physical fatigue?

 

[forestglip]

How have they showed that REM doesn’t play a role in recovery from physical fatigue?

It seems like they're just inferring that based on the person having less REM after these marathons.

Some more from the paper about intense exercise's effect on sleep:

For example, elite athletes seem to sleep less, have more fragmented sleep, and have poorer sleep efficiency than the general population (see Gupta et al., 2017, for a review; Juliff et al., 2015; Knufinke et al., 2018; Nikolaidis et al., 2023). In addition, sleep stage distribution is affected by exercise because slow-wave sleep (SWS) increases after periods of intense physical exercise (Halson & Juliff, 2017; Marshall & Turner, 2016) and REM sleep decreases in those cases (Driver & Taylor, 2000).

 

[Utsikt]

It seems like they're just inferring that based on the person having less REM after these marathons.

Some more from the paper about intense exercise's effect on sleep:

Wouldn’t it be possible that REM helps with recovery, but that doing too much disrupts REM for other reasons?

 

[forestglip]

Wouldn’t it be possible that REM helps with recovery, but that doing too much disrupts REM for other reasons?

That would be my first guess on seeing that data.

This similar statement from the text suggests they don't necessarily think REM decreased because it isn't necessary, but that slow wave sleep increased because it is important in recovery:

In fact, and in agreement with previous results (Halson & Juliff, 2017; Marshall & Turner, 2016; Shapiro et al., 1981), a greater amount of SWS was observed in the non-recovery condition [immediately after marathons], thus supporting the idea of its essential role in physical recovery.

Edit: But the fact that total sleep time decreased suggests to me that these aren't changes meant for better recovery. If slow wave sleep helps recover, how would it help to decrease overall sleep time as well?

 

[Utsikt]

That would be my first guess on seeing that data.

This similar statement from the text suggests they don't necessarily think REM decreased because it isn't necessary, but that slow wave sleep increased because it is important in recovery:

Pain probably also correlated with recovery, and a host of different variables as well. Only based on their text I don’t think they make a very good argument for why their interpretation is the most likely one.

 

[forestglip]

I calculated the actual time in each stage using the percentages from Table 2. Minutes of slow wave sleep was modestly higher (11.8%) at night 1 compared to night 7. But minutes of REM was much lower (-63.7%) on night 1 compared to night 7.

It looks like the main effect of the marathons was reducing total sleep time and REM, not increasing SWS to somehow assist in recovery.

	Non-recovery (night 1 post challenge)	Partial recovery (night 7 post challenge)	Baseline (night 21 post-marathon; complete recovery)
Total sleep time (min)	315.50	404.00	482
REM (min)	45.4	124.9	102.7
SWS (min)	121.5	108.7	128.7
Stage 1 (min)	36.6	23.8	40.0
Stage 2 (min)	112.0	146.7	210.2

(Loving the new table function!)

 

[forestglip]

I wish they would have tested more nights. REM looks to have mostly recovered by night 7, so far all we know, it was only really low on a single night immediately after running. Total sleep time does seem to still be a little low at night 7 (6.7 hrs) compared to night 21 (8.0 hrs).