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Excessive daytime sleepiness can significantly impair quality of life, work performance, and a person's ability to carry out everyday tasks. It often occurs in people with obstructive sleep apnea and shift work sleep disorder. One of the medications used to promote wakefulness is modafinil.
But how effective is it at reducing daytime sleepiness? Does the medication actually improve the ability to stay awake, maintain attention, and perform everyday tasks? And what risks should be considered when taking it?
In 2026, the journal Sleep Medicine published a systematic review and meta-analysis of randomized controlled trials examining the efficacy and safety of modafinil in adults with excessive daytime sleepiness associated with obstructive sleep apnea or shift work.
The results showed that modafinil may improve objectively measured wakefulness, as well as certain measures of clinical status and attention. However, the results of subjective sleepiness assessments were less conclusive, and the use of the medication was associated with an increased risk of certain adverse effects.
Excessive daytime sleepiness (EDS) is a condition in which a person experiences a strong need to sleep or has difficulty staying awake when they are expected to be active. It may manifest as falling asleep in inappropriate situations, reduced concentration, slower reaction times, and difficulty performing routine tasks.
Among the causes of excessive daytime sleepiness examined in the study, particular attention was given to two conditions.
Obstructive sleep apnea is a breathing disorder in which the upper airway repeatedly narrows or becomes blocked during sleep. As a result, sleep may be interrupted many times, reducing its restorative effects. Consequently, a person may experience fatigue and sleepiness even after spending the night in bed.
In some patients, daytime sleepiness persists even while they are receiving treatment for sleep apnea. In such cases, it is important to assess whether medications that promote wakefulness can provide additional benefits.
Shift work sleep disorder occurs when a work schedule conflicts with the body's natural circadian rhythms. This may affect people who work at night, rotate between different shifts, or have to sleep at times that do not align with their internal biological clock.
This disorder may be associated with sleepiness during work, difficulty falling asleep at the intended time, and insufficient sleep duration. Modafinil has been studied as a medication that may help maintain wakefulness in these circumstances.
The authors of the systematic review combined data from nine randomized controlled trials involving a total of 1,265 participants. The meta-analysis assessed the outcomes of modafinil compared with placebo and also examined adverse effects.
| Measure | Key Findings |
|---|---|
| Number of studies | 9 randomized controlled trials |
| Total number of participants | 1,265 participants |
| Main conditions | Obstructive sleep apnea and shift work sleep disorder |
| Objective wakefulness in sleep apnea | Statistically significant improvement on the Maintenance of Wakefulness Test (MWT): an average of 2.95 minutes compared with placebo |
| Subjective sleepiness | The overall analysis of continuous Epworth Sleepiness Scale (ESS) scores found no statistically significant difference between modafinil and placebo |
| Attention and clinical improvement | Positive results were observed for selected measures of clinical status and vigilance |
| Results in shift workers | Two studies involving 487 participants reported improvements in selected measures of sleepiness, wakefulness, and functioning |
| Safety | A higher risk of treatment discontinuation due to adverse effects, along with more frequent reports of headache, insomnia, nausea, and anxiety |
Important: These findings do not mean that modafinil is equally effective for all patients or that it eliminates the underlying cause of sleepiness. The authors noted differences between the results of individual assessment methods, and the certainty of the evidence regarding subjective sleepiness was low. The findings should therefore be interpreted in the context of the patient's specific condition and the limitations of the studies.
The researchers searched for relevant scientific publications in the MEDLINE/PubMed, EMBASE, LILACS, and CENTRAL databases, as well as in clinical trial registries. The search covered the period from the beginning of database indexing through May 2026.
The review included randomized controlled trials involving adults with excessive daytime sleepiness associated with obstructive sleep apnea or shift work sleep disorder. The studies compared modafinil with placebo.
Efficacy was assessed using several measures that examined sleepiness from different perspectives:
The authors used the RoB 2 tool to assess the risk of bias and the GRADE system to evaluate the certainty of the evidence. This allowed them to assess not only the direction of the findings but also the level of confidence in them.
Most of the data in the systematic review concerned patients with obstructive sleep apnea (OSA) who experienced excessive daytime sleepiness. The researchers assessed modafinil using subjective questionnaires, objective wakefulness tests, and measures of everyday functioning.
The Epworth Sleepiness Scale (ESS) is a questionnaire used to estimate the likelihood of falling asleep in various everyday situations. It is widely used to assess excessive daytime sleepiness.
In the meta-analysis, neither changes in ESS scores from baseline nor scores at the end of the studies demonstrated a statistically significant advantage of modafinil over placebo. However, analyses based on predefined treatment-response criteria generally favored modafinil.
It is important to distinguish between these findings: some patients may have reached a predefined threshold for improvement, while the overall mean change in the group did not confirm a statistically significant advantage. The authors rated the certainty of the evidence for ESS as low.
The Maintenance of Wakefulness Test (MWT) was used to assess a person's ability to remain awake. Unlike a questionnaire, this test measures the ability to resist falling asleep under standardized conditions.
Based on the pooled study results, the MWT score at the end of follow-up was an average of 2.95 minutes higher in the modafinil group than in the placebo group. The 95% confidence interval ranged from 0.66 to 5.23 minutes, with a p-value of 0.01. This indicates a statistically significant advantage for modafinil on this measure.
The certainty of the evidence for MWT was rated as moderate. However, this result relates to a specific test conducted under study conditions and does not, by itself, prove that the medication eliminates all symptoms of sleepiness or affects the underlying cause of sleep apnea.
The studies also reported improvements on the Clinical Global Impression of Change (CGI-C) scale and in selected measures of vigilance. These findings complement the MWT results and suggest possible improvements in certain aspects of wakefulness and functioning.
However, the results from different assessment methods were not entirely consistent. Therefore, the efficacy of modafinil should be considered in relation to the specific outcome being measured, rather than summarized as an equal improvement for all patients.
Shift work sleep disorder (SWSD) may occur when a work schedule does not align with the natural sleep-wake cycle. A person may experience severe sleepiness while working at night or have difficulty sleeping when they need to rest.
The systematic review included two randomized controlled trials involving a total of 487 participants to assess modafinil for SWSD.
The results suggested improvements in some measures of objective wakefulness, subjective sleepiness, and selected functional outcomes. However, the effects were not consistent across all assessed measures. Because the data were not reported in sufficiently comparable formats, the authors could not conduct a full quantitative meta-analysis for this condition.
Thus, the SWSD studies suggest that modafinil may benefit certain aspects of sleepiness, but they do not establish that its effects are consistent across all patients or all aspects of everyday functioning.
Overall, the systematic review found that, in excessive daytime sleepiness associated with obstructive sleep apnea, modafinil had an advantage over placebo on an objective wakefulness test and selected other measures. However, the mean ESS results did not demonstrate a statistically significant advantage.
For shift work sleep disorder, the results were promising for selected measures but remained inconsistent. For both conditions, it is therefore important to consider not only potential efficacy but also the risk of adverse reactions and the patient's individual circumstances.
In addition to efficacy, the systematic review assessed the tolerability of modafinil and the frequency of adverse reactions. According to the pooled randomized controlled trial data, the medication was associated with an increased risk of certain adverse effects compared with placebo.
In particular, participants taking modafinil were more likely to discontinue treatment because of adverse events. The relative risk of such discontinuation was 2.5 times higher than with placebo.
| Adverse reaction | Relative risk compared with placebo |
|---|---|
| Discontinuation due to adverse effects | 2.50 |
| Headache | 1.38 |
| Insomnia | 4.64 |
| Nausea | 2.57 |
| Anxiety or nervousness | 3.08 |
These values represent relative risks, not the percentage probability of experiencing an adverse reaction. For example, a relative risk of 2.50 does not mean that adverse effects occurred in 250% of participants. Absolute probabilities require the baseline event rates in the relevant groups.
The largest relative increase among the listed reactions was observed for insomnia. Nausea, anxiety or nervousness, and headache were also reported more frequently in the modafinil group. These findings highlight the importance of assessing medication tolerability, not just its potential effect on wakefulness.
The meta-analysis results should be interpreted in light of several limitations.
Overall, the review summarizes available randomized trial findings but does not eliminate uncertainty regarding every aspect of modafinil's efficacy and safety.
A systematic review and meta-analysis of nine randomized controlled trials involving 1,265 participants found that modafinil may improve selected measures of wakefulness in adults with excessive daytime sleepiness associated with obstructive sleep apnea.
The pooled analysis showed a statistically significant advantage for modafinil over placebo on the Maintenance of Wakefulness Test (MWT). However, mean Epworth Sleepiness Scale (ESS) scores did not show a statistically significant advantage, although analyses based on treatment-response criteria generally favored the medication.
For shift work sleep disorder, studies suggested improvements in some measures of sleepiness and wakefulness, but the findings were inconsistent.
Another important finding was the increased risk of adverse reactions, including insomnia, headache, nausea, and anxiety or nervousness. These results should not be interpreted as a reason to use the medication without medical supervision.
Modafinil does not address the underlying cause of obstructive sleep apnea and does not replace appropriate treatment for the condition. A healthcare professional should make decisions about its use after evaluating the causes of sleepiness, coexisting conditions, potential contraindications, and risks.
The results showed a statistically significant advantage for modafinil over placebo on the MWT in patients with obstructive sleep apnea. However, no statistically significant advantage was found in mean ESS scores. The conclusion therefore depends on the specific outcome measure.
At the end of the studies, the mean difference between groups was 2.95 minutes in favor of modafinil. The 95% confidence interval ranged from 0.66 to 5.23 minutes. This is a pooled result and does not guarantee the same effect for every individual.
Two studies involving 487 participants suggested improvements in selected measures of wakefulness and sleepiness. However, results were inconsistent across outcomes, and there was insufficient data for a full meta-analysis.
The meta-analysis found increased relative risks of headache, insomnia, nausea, and anxiety or nervousness. Treatment discontinuation due to adverse events was also more frequent.
No. Modafinil may affect excessive daytime sleepiness, but it does not treat obstructive sleep apnea itself. It does not replace diagnosis or treatment of the underlying condition and should only be considered when medically indicated.
This meta-analysis studied adults with excessive daytime sleepiness associated with specific sleep disorders. It does not establish the benefit-risk balance for healthy people seeking to improve productivity. Using the medication without medical assessment is not recommended.
Silva de Lima M. et al. “Modafinil for excessive daytime sleepiness: A systematic review and meta-analysis of randomized controlled trials.” Sleep Medicine, 2026.
DOI: 10.1016/j.sleep.2026.109116.
PubMed publication: view the study record.
Important: This material is for informational purposes only and is not medical advice. It does not replace consultation with a healthcare professional, diagnosis, or prescribed treatment.
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