Table 2.
Number of comparisons which could be considered for meta-analytic calculations for each disorder and for each sleep variable
| SEI | SOL | TST | NA | WAKE/ WASO(%)1 |
REML | REMD | S1(%) | S2(%) | SWS(%) | REM(%) | |
|---|---|---|---|---|---|---|---|---|---|---|---|
|
Sleep Efficiency Index |
Sleep Onset Latency |
Total Sleep Time |
Number of Awakenings |
Wake after sleep onset |
REM Latency |
REM Density |
Duration of stage 1 sleep |
Duration of stage 2 sleep |
Duration of Slow wave sleep |
Duration of REM sleep |
|
| Affective disorders (N=55)2 | 48 | 52 | 36 | 10 | 15 | 52 | 38 | 43 | 42 | 46 | 49 |
| MDD (N=50) | 44 | 48 | 33 | 10 | 15 | 47 | 35 | 40 | 39 | 43 | 45 |
| SAD (N=3) | 3 | 3 | 3 | / | / | 3 | / | / | / | / | 3 |
| Anxiety disorders3 (N=21) | 17 | 19 | 19 | 11 | 3 | 18 | 14 | 14 | 15 | 14 | 17 |
| PD (N=4) | 4 | 4 | 3 | 3 | / | 4 | / | / | 3 | 4 | 3 |
| PTSD (N=13) | 10 | 11 | 13 | 6 | / | 10 | 9 | 9 | 9 | 11 | 11 |
| Eating disorders (N=5)4 | |||||||||||
| Anorexia nervosa (N=5) | 4 | 3 | 3 | / | / | 5 | / | 4 | 4 | 4 | 4 |
| Externalizing disorders (N=6)5 | |||||||||||
| ADHD (N=6) | 6 | 6 | 5 | 4 | 5 | 6 | / | 6 | 6 | 6 | 6 |
| Pervasive developmental disorders (N=10)6 | |||||||||||
| Asperger syndrome (N=3) | 3 | 3 | 3 | / | / | 3 | / | 3 | 3 | 3 | 3 |
| Autistic disorder (N=7) | 7 | 6 | 6 | 6 | 7 | 6 | 3 | 7 | 7 | 7 | 7 |
| Personality disorders (N=5)7 | |||||||||||
| Borderline personality disorder (N=5) | 4 | 5 | 3 | 3 | 4 | 5 | 3 | 5 | 5 | 5 | 5 |
| Schizophrenia8 (N=10) | 10 | 10 | 8 | 6 | 3 | 10 | 9 | 9 | 9 | 10 | 10 |
/ indicates that none or less than 3 studies were available and for this reason no meta-analysis was conducted.
ABBREVIATIONS: MDD= Major Depression Disorder; SAD= Seasonal Affective Disorder; PD= Panic Disorder; PTSD= Post-Traumatic Stress Disorder; AN= Anorexia Nervosa; ADHD= Attention Deficit Hyperactivity Disorder.
WAKE and WASO generally refer to 2 different parameters: while WASO is generally defined as the difference between SPT and TST; WAKE is generally defined as the amount of wake stages as identified through polysomnographic recordings. Nevertheless, in our sample of studies the 2 parameters were often confused, with one study using the first definition for a parameter named WAKE or the other way round. Due to the closeness of the 2 definitions we decide to consider them in one single variable in order to evaluate the largest number of studies possible.
The group “affective disorders” included studies evaluating mixed affective disorders (e.g. mixed unipolar and bipolar affective disorders; this group was not further evaluated); studies focusing on major depression and studies focusing on seasonal affective disorders.
The group “anxiety disorders” included studies evaluating mixed anxiety disorders, social phobia, specific phobia, obsessive compulsive disorder, panic disorder and post-traumatic stress disorder. Because of the number of studies available, only panic disorder and post-traumatic stress disorder could be further evaluated in subgroup analyses.
The group “eating disorders” included studies focusing on anorexia nervosa.
The group “externalizing disorders” included 6 studies focusing on Attention Deficit Hyperactivity Disorder and 1 study evaluating Conduct disorder. Thus, only the 6 studies analyzing PSG in patients with Attention Deficit Hyperactivity Disorder were considered in the meta-analysis.
The group “pervasive developmental disorders” included 7 studies in total, 2 of them included both a group of patients with autism and a group of patients with Asperger syndrome and compared them with the same control group. For this reason, we analyzed the two disorders separately and no analyses for the category “pervasive developmental disorders” were performed.
The group “personality disorders” included 5 studies focusing on Borderline Personality Disorder, and 1 study evaluating Antisocial Personality Disorder. Thus, only the 5 studies analyzing PSG in patients with Borderline Personality Disorder were considered in the meta-analyses.
For schizophrenia, no further subgroups were considered.