Table 1.
Representative studies on self-reported sleep, sleep disturbances, and hippocampal volume
| Reference | N | Population | Result | Comment |
|---|---|---|---|---|
| Patients with sleep disorders (patients/ controls) | ||||
| Dusak et al. [21] | 22/20 | Obstructive sleep apnea | + | Smaller hippocampus in sleepy patients (n = 12), negative correlation with excessive daytime sleepiness. |
| Joo et al. [22] | 36/36 | Narcoleptics with cataplexy | + | Smaller hippocampus in patients, volume correlated with mean sleep and REM sleep latencies. |
| Joo et al. [19] | 27/30 | Primary insomnia | + | Smaller volume in patients, CA1 volume correlated with PSQI and higher arousal index (polysomnography) in the patients. |
| Morrell et al. [20] | 7/7 | Obstructive sleep apnea | + | Lower GM concentration in left hippocampus in patients. |
| Morell et al. [27] | 60/60 | Obstructive sleep apnea | No differences in the hippocampus, smallerGM volume in right middle temporal gyrus in the patients. | |
| Neylan et al. [23] | 17/10 | PTSD | + | Insomnia Sleep Index and PSQI associated with smaller volumes of CA3/dendate subfields in the combined sample. No significance for other subfields. In total 5 subfields were tested. |
| Noh et al. [24] | 20/20 | Primary insomnia | −/+ | No difference in hippocampus volume. In patients, hippocampus correlated negatively with duration of insomnia and the arousal index. |
| Riemann et al. [18] | 8/8 | Primary insomnia | + | Smaller hippocampal volume in patients. |
| Rosenzweig et al. [28] | 32/32 | Obstructive sleep apnea | − | Larger volume in patients |
| Sforza et al. [74] | 232 | Older, sleep-disordered breathing | + | Negative correlation between worse sleep and hippocampal volume |
| Spiegelhalder et al. [25] | 28/38 | Primary insomnia | − | No significant results |
| Winkelman et al. [26] | 20/15 | Primary insomnia | − | No main effect on hippocampal volume. Actigraph measures of poor sleep maintenance were associated with smaller volume in patients. |
| Normal controls | ||||
| Alperin et al. [29] | 69 | Older | + | Smaller hippocampi in poor sleepers, shorter sleep duration correlated with lower volume in the full sample. |
| Carvalho et al. [30] | 1,374 | Middle-aged/older | + | Fatigue related to smaller hippocampal volume |
| Lo et al. [33] | 119 | Middle-aged/older, longitudinal | − | No with hippocampus change |
| Sexton et al. [32] | 147 | Adult lifespan, longitudinal | − | No relationship between PSQI and hippocampal volume change |
| Sabeti et al. [31] | 79 | 90+ years | − | No relationships. |
| Taki et al. [75] | 290 | Children/adolescents | + | Hippocampal body correlated with sleep duration during weekdays. |
Result: “−” indicates no relationship between hippocampus volume and sleep or an inverse relationship (e.g. higher volume in patients). “+” indicates the expected relationship between hippocampus volume and sleep, for example, smaller volume in patients or a negative correlation between sleep problems and volume. Results for other brain structures than the hippocampus are not reported.