These findings provide tentative support for a night-to-day, sleep-to-grief pathway, although both small effect sizes and variability in results underscore the need for replication in larger samples.
Key Findings
Results
Lower sleep quality was associated with increased prolonged grief severity during the following day, controlling for previous-day PG levels.
This effect was found in the primary linear mixed model analyses using 14-day EMA data
The effect was no longer statistically significant in sensitivity analyses restricted to participants with more complete sleep data (≥50% of assessments)
Effect sizes were described as small
The analysis controlled for previous-day PG levels to isolate the lagged within-person effect
Results
Prolonged grief symptoms did not predict sleep quality the following night.
Within-person lagged effects of PG on next-night sleep quality were not statistically significant
This suggests the association is directional (sleep-to-grief) rather than bidirectional in the short term
The sample consisted of 46 traumatically bereaved adults with a median time since loss of 3.8 years
PG symptoms were assessed 5 times per day and sleep quality each morning via a smartphone app
Results
The association between sleep quality and prolonged grief was strongest in the morning and attenuated later in the day.
This pattern was identified in exploratory post hoc analyses
The finding suggests a time-of-day moderation of the sleep-to-grief effect
The attenuation across the day indicates the influence of poor sleep on grief symptoms may dissipate as the day progresses
These are described as exploratory findings requiring replication
Methods
The study sample consisted of traumatically bereaved adults assessed over a 14-day ecological momentary assessment protocol.
Sample size was 46 traumatically bereaved adults
Mean age was 56.0 years and 78% were female
Median time since loss was 3.8 years
PG symptoms were assessed 5 times per day via a smartphone app
Linear mixed models were used to examine within-person lagged effects
Background
The directionality and timing of effects between sleep and prolonged grief had been unclear prior to this study despite existing cross-sectional and longitudinal evidence linking PGD with poor sleep.
Prior research had established a link between prolonged grief disorder (PGD) and sleep disturbances but could not clarify directionality
The EMA design was employed specifically to examine day-to-day, within-person associations
Sleep disturbances are described as common in bereavement, especially among those with PGD
The authors note the need for replication in larger samples due to small effect sizes and variability in results
What This Means
This research suggests that for people who have experienced a traumatic loss, the quality of their sleep at night may influence how intensely they experience grief symptoms the following day. Using a smartphone-based study where 46 bereaved adults reported their grief symptoms five times a day and rated their sleep each morning over two weeks, researchers found a tentative 'sleep-to-grief' pattern — poor sleep was linked to higher grief levels during the next day. Importantly, the reverse was not found: higher grief symptoms on a given day did not appear to worsen sleep that night.
The effect of sleep on grief was most noticeable in the morning and seemed to fade as the day went on, suggesting that the impact of a bad night's sleep on grief may gradually diminish over the course of the day. However, these findings come with important caveats: the effect sizes were small, results were not consistent across all analyses (the association became non-significant when only participants with more complete data were included), and the sample of 46 people is relatively small.
This research suggests that poor sleep may play a role in temporarily worsening grief symptoms in people who have lost someone to a traumatic event, pointing to sleep as a potentially meaningful target in understanding and supporting bereaved individuals. The authors emphasize that these findings are preliminary and that larger studies are needed to confirm whether improving sleep could help reduce the severity of prolonged grief symptoms.
Kivelä L, Pociūnaitė-Ott J, Lenferink L. (2026). Sleepless Longing: Bidirectional Associations Between Sleep Quality and Prolonged Grief in Daily Life After Traumatic Loss.. Clinical psychology & psychotherapy. https://doi.org/10.1002/cpp.70238