Imagine you have had a poor night’s sleep. Maybe you went to bed far too late, had to get up early, or woke up still exhausted after what ought to have been a full night’s rest.
For the remainder of the day, you feel drowsy and unable to concentrate. Activities that normally feel enjoyable or exciting bring much less pleasure. You lack the energy to exercise, so you give it a miss. You do not feel up to seeing friends, so you cancel plans.
That evening, as you try to drift off, you replay the difficult day and begin to feel anxious about tomorrow. Rather than getting the restorative sleep you need, you end up with another poor night. Before long, you are stuck in a vicious cycle of inadequate sleep and low mood.
Sleep and mental health problems commonly occur together. Sleep difficulties are a core symptom of depression. Beyond that, strong evidence shows that sleep problems contribute to a range of mental health disorders, including schizophrenia and post-traumatic stress disorder, or PTSD.
At the same time, mental health affects how well we sleep. Distressing thoughts and difficulty relaxing can make it hard to fall asleep or stay asleep, worsening existing sleep problems.
These issues can be especially pronounced during pregnancy, when the circular relationship between insufficient sleep and mental health challenges can have harmful effects on mothers and their children.
We are a developmental psychologist and a doctoral student in psychology who examine sleep and mental health from pregnancy through adulthood. In our research, we witness the effects of sleep and mental health problems directly.
Because sleep and mental health are so tightly intertwined, it is unsurprising that each can intensify the other. However, this entanglement can make treatment more difficult.
The biology of sleep and mental health
Researchers and clinicians understand that sleep is vital for the body and brain to work properly.
Sleep helps establish circadian rhythms, which optimise alertness during the day and rest at night. As daylight fades in the evening, the brain produces more of the hormone melatonin, and core body temperature drops to encourage sleep. When the brain registers sunlight, melatonin production decreases and body temperature rises to support wakefulness.
While light and darkness are the most important cues the brain uses to determine when you should be awake versus asleep, other factors-such as stress, disruptions to daily routines and social interactions-can also upset your circadian rhythm.
Circadian rhythms also influence other key biological processes, including the body’s production of the stress hormone cortisol. Cortisol follows a daily pattern: it is highest shortly after waking in the morning and lowest in the middle of the night.
When normal sleep is disrupted, it can become harder to regulate cortisol levels across the day. This can negatively affect mental health and reduce a person’s ability to manage stress effectively.
Sleep is also central to the immune system functioning properly, which has consequences for both mental and physical health. Sleep disturbances have been associated with weaker immune responses to viruses and other immune challenges, making it more difficult to stay well and to recover after illness.
Sleep disruption can also increase inflammation, when the immune system’s natural responses become overactive. Inflammation contributes to both mental and physical health problems, including depression, heart disease and cancer.
How poor sleep drives behaviour changes
Long-term disruptions to a person’s natural circadian rhythm-such as in people who work night shifts or alternate between day and night shifts-are linked with higher risk of both depression and anxiety.
Shift work is an extreme example of disturbing the usual pattern of sleeping at night. But less severe sleep problems-such as not getting enough sleep or waking up feeling tired-are also harmful to mental health.
Sleep disruption makes it harder to regulate emotions. Too little sleep, or sleep of poor quality, makes everyday stressors more difficult to handle. That is because adequate sleep is needed for effective problem-solving, memory and attention. When emotion regulation and stress-management capacities are both impaired, mental health difficulties are more likely.
A major reason poor sleep and mental health struggles can become so severe-and so hard to treat-is that without sufficient sleep it is difficult to find the energy for healthy activities such as exercising and maintaining social relationships.
In addition, when decision-making is affected by poor sleep and negative emotions, people are more likely to turn to alcohol, drugs and unhealthy foods to cope with stress. These unhealthy behaviours can then reinforce the cycle by further interfering with sleep.
Pregnancy, sleep and mental health: a damaging cycle
The back-and-forth cycle between poor sleep and mental health challenges can be particularly problematic during pregnancy.
Typical pregnancy symptoms include nausea, heartburn, back and joint pain, cramps, frequent urination and contractions-each of which can make restful sleep harder to achieve.
Unfortunately, about 76% of pregnant women report sleep problems at some point during pregnancy, compared with only 33% in the general population. Similarly, around 1 in 5 pregnant women in the United States experience mental health problems such as anxiety and depression.
Our team’s new research, published in December 2025, adds to the evidence linking sleep and mental health. We found that during pregnancy, mental health problems contribute to sleep problems over time-and that sleep problems, in turn, can worsen mental health problems.
This pattern can also negatively affect the fetus and the child after birth.
Prenatal sleep problems, including short sleep, sleep apnoea and restless sleep, can increase the likelihood of preterm birth and low birth weight in newborns.
A large study in Sweden in 2021 reported that pregnant women who often worked night shifts or rapidly switched between night and day work in early pregnancy had a three-to-four times higher risk of preterm birth.
Preterm birth and low birth weight are linked with increased cardiovascular risk for both mothers and their offspring.
Prenatal maternal sleep problems may also be associated with later difficulties in children’s development. A review we also published in 2025 found that children of mothers who experienced sleep problems during pregnancy are more likely to have sleep problems themselves.
Our review further reported that children whose mothers had prenatal sleep problems have a higher likelihood of developing obesity and show more behavioural problems in childhood.
Speaking with your doctor about these concerns
In our view, screening for sleep problems should be routine at medical appointments, given the potential consequences of insufficient sleep for both mothers and their babies.
If someone close to you is pregnant, consider asking how they are sleeping and how they are feeling. If they mention ongoing sleep problems or emotional or behavioural changes, you could ask whether they have discussed this with their doctor.
They may feel overwhelmed and may need support to raise these issues with their doctor or help locating resources. The Sleep Foundation website provides a list of sleeping tips for pregnant women, along with guidance on when to speak with a doctor.
If you are the person dealing with these problems, you can tell your doctor about your sleep difficulties and ask for advice on improving sleep.
If you are experiencing depression or anxiety, let your doctor know and ask for resources. There are mental health resources specifically for pregnancy that can help. You can also locate mental health professionals via Psychology Today’s find-a-therapist tool.
Healthy sleep is essential for supporting mental health during pregnancy and throughout life.
Jenalee Doom, Associate Professor of Psychology, University of Denver and Melissa Nevarez-Brewster, Ph.D. student in Developmental Psychology, University of Denver
This article is republished from The Conversation under a Creative Commons licence. Read the original article.
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