You're not sleeping well. You're also feeling anxious and low. But which is causing which?
This question matters because the answer determines what to fix first.
The bidirectional relationship
Sleep and mental health don't just correlate. They cause each other. Research confirms this runs both directions:
- Poor sleep increases your risk of depression and anxiety
- Depression and anxiety disrupt your sleep
- Improving sleep reduces depression and anxiety symptoms
- Treating depression and anxiety improves sleep
People with insomnia are 10 times more likely to have depression and 17 times more likely to have anxiety. But the relationship isn't just correlation. Studies show sleep disturbance actually predicts future mental health problems.
This creates a cycle. Bad sleep worsens mood. Bad mood worsens sleep. Without intervention, both spiral downward together.
Which comes first?
Research suggests sleep disturbance is often the stronger predictor. In longitudinal studies, sleep problems frequently precede depression and anxiety symptoms, sometimes by weeks or months.
This matters for treatment. If sleep is the root cause, treating only the depression or anxiety won't fully work. The sleep problem will keep pulling you back down.
But individual patterns vary. For some people, anxiety is the primary driver, and the racing thoughts at 2am are a symptom, not a cause. Tracking helps you figure out which pattern applies to you.
What the research shows
A meta-analysis of randomized controlled trials found that improving sleep quality led to significant improvements in:
- Depression symptoms (moderate effect)
- Anxiety symptoms (moderate effect)
- Stress (small to moderate effect)
- Rumination (moderate effect)
Critically, they found a dose-response relationship: bigger improvements in sleep correlated with bigger improvements in mental health. This suggests sleep isn't just associated with mental health but causally connected.
How to track the connection
You need two types of data: sleep metrics and mental health scores.
Sleep metrics to track:
- Total sleep time (hours)
- Sleep quality (subjective 1-10 rating)
- Time to fall asleep
- Number of wake-ups
- How rested you feel in the morning
You can use a sleep tracker, app, or simple self-report. Precision matters less than consistency.
Mental health assessments:
- PHQ-9 for depression
- GAD-7 for anxiety
- DASS-21 for both plus stress
Take the mental health assessment weekly. Record sleep data daily or at least note your average for the week.
What to look for
After a few weeks, patterns emerge:
Sleep leads mood: Your sleep worsens first, then mental health scores rise 1-2 weeks later. When sleep improves, scores drop afterward. This suggests sleep is the driver.
Mood leads sleep: Mental health scores spike first, then sleep deteriorates. Treating the anxiety or depression should help the sleep.
They move together: Both worsen and improve simultaneously. The cycle is locked. You might need to target both.
No clear relationship: Sleep and mental health fluctuate independently. They may not be strongly connected for you, or other factors are more important.
Breaking the cycle
If sleep appears to be driving your mood problems, targeting sleep directly often works better than treating the mood symptoms alone.
Cognitive Behavioral Therapy for Insomnia (CBT-I) is the most effective treatment for chronic insomnia, outperforming sleeping pills with lasting effects. A large clinical trial showed CBT-I also reduced symptoms of depression, anxiety, and even psychotic experiences.
Sleep hygiene basics:
- Consistent wake time (even weekends)
- No screens 1 hour before bed
- Cool, dark room
- Limit caffeine after noon
- No alcohol close to bedtime (it disrupts sleep quality)
If anxiety is driving the sleep problem: The racing thoughts keeping you awake need direct treatment. CBT for anxiety, relaxation techniques, or sometimes medication may help more than sleep-focused interventions.
Using your data
Once you have 4-6 weeks of tracking, you can see your pattern:
Example 1: Sleep-driven
- Week 1: Sleep average 5.5 hrs, PHQ-9 = 8
- Week 2: Sleep average 5 hrs, PHQ-9 = 10
- Week 3: Sleep average 4.5 hrs, PHQ-9 = 13
- Week 4: Started sleep hygiene routine, sleep = 6.5 hrs
- Week 5: Sleep = 7 hrs, PHQ-9 = 9
- Week 6: Sleep = 7 hrs, PHQ-9 = 6
Sleep improved first, then mood followed. Focus on maintaining good sleep.
Example 2: Anxiety-driven
- Week 1: GAD-7 = 8, sleep average 6.5 hrs
- Week 2: Work stress, GAD-7 = 14, sleep average 5 hrs
- Week 3: GAD-7 = 16, sleep average 4.5 hrs
- Week 4: Started therapy, GAD-7 = 12, sleep = 5 hrs
- Week 5: GAD-7 = 9, sleep = 6 hrs
- Week 6: GAD-7 = 7, sleep = 7 hrs
Anxiety spiked first and drove the sleep problem. As anxiety improved, sleep followed.
The feedback loop advantage
The bidirectional relationship is also an opportunity. Because sleep and mood reinforce each other, improving one helps improve the other.
This means you don't necessarily need to identify the "true" cause. Sometimes intervening on whichever is easier to change can start a positive spiral. Better sleep improves mood. Better mood improves sleep. Each improvement makes the next one easier.
Tracking shows you whether this positive cycle is happening, or whether you're stuck.
When to get help
Some patterns warrant professional attention:
- Sleep problems lasting more than 3 weeks with no clear cause
- PHQ-9 or GAD-7 scores in the moderate range (10+) that aren't improving
- Severe insomnia (sleeping less than 4-5 hours consistently)
- Sleep problems that don't respond to basic sleep hygiene
- Any mention of thoughts of self-harm
A sleep specialist can evaluate for underlying conditions (sleep apnea, restless leg syndrome). A mental health provider can address anxiety or depression that might be driving the sleep problem.
Getting started
1. This week: Start tracking sleep. Note hours slept and a 1-10 quality rating each morning.
2. Also this week: Take the DASS-21 or both the PHQ-9 and GAD-7.
3. Weekly: Repeat the mental health assessment. Calculate your average sleep for the week.
4. After 4-6 weeks: Look at the data. Which moved first? Which seems to predict the other?
5. Decide on an intervention: Target sleep, target mood, or both. Keep tracking to see if it works.
Sleep and mental health are linked. Tracking reveals how they're linked for you specifically. That knowledge tells you where to focus your energy.
Start tracking your mental health
Survey Doctor makes it easy to take the PHQ-9, GAD-7, or DASS-21 on a regular schedule and see your scores over time. Pair your mental health data with a simple sleep log to uncover your personal patterns. Take your first assessment.