Can pain trigger nighttime arousal and fragmented sleep, while disrupted sleep increases next-day pain sensitivity?

Pain and sleep disturbance can reinforce one another, creating a clinically relevant cycle: pain may interrupt sleep, and repeated sleep disruption can increase pain sensitivity the following day.

Clinical evidence

• Pain disrupting sleep: Controlled polysomnography provides direct evidence that acute intramuscular pain during sleep disrupts both light and deep NREM sleep and worsens perceived sleep quality the next morning. In chronic-pain populations, a systematic review of 29 controlled PSG studies commonly found more awakenings and wake after sleep onset (WASO), with lower sleep efficiency. Effects vary across pain conditions and individuals, so pain is not the sole driver of nocturnal waking.
• Sleep disruption increasing pain: The strongest evidence is experimental. In a randomized crossover study of 95 healthy adults, two nights of forced awakenings lowered heat-pain thresholds versus undisturbed sleep, indicating increased next-day heat-pain sensitivity. A related crossover study observed the effect in both women and men. Review evidence indicates a small overall hyperalgesic effect, most apparent after repeated fragmentation; one disrupted night and pressure-pain thresholds show less consistent effects.
• In daily-life studies of adults already experiencing pain, poorer sleep efficiency and perceived sleep quality predicted greater pain the next day, whereas sleep duration alone did not.

Mechanistic context

• Forced awakenings reduce N3/slow-wave sleep. In the crossover experiment, reduced N3 was followed by increased stimulated monocyte production of IL-6 and TNF-α, statistically accounting for part of the change in heat-pain threshold. This supports an inflammatory pathway linking fragmented sleep to heightened nociceptive sensitivity, although it does not establish inflammation as the only mechanism.

Bottom line

• Pain can contribute to nighttime arousal and fragmented sleep, while repeated sleep fragmentation can heighten next-day pain sensitivity—most clearly for heat pain after two disrupted nights. For a 64-year-old woman with pain and poor sleep, addressing sleep continuity may be a meaningful adjunct to pain management, particularly when awakenings are recurrent.