General HealthPregnancy and Newborn Health

Pregnancy: Role of Sleep Cycles in Postpartum Depression

During pregnancy, sleep loss and inadequate sleep is a common problem faced by women which can exacerbate postpartum psychiatric and neurotic disorders.

Have you observed your activity patterns cycles in a day where you are the most active at specific time points?. This is called a chronotype. Chronotype is a circadian type assigned to every individual’s peak activity time points. Understanding the chronotype helps us define our peak productivity time and hence have a better planned day.

Scientists have classified chronotypes into different types based on the day-night cycles, sleep and activity patterns in specific animals. Larks and owls are one of the chronotype classification used for peak activity during the early day (early chronotype) and peak activity during the late night (late chronotype) respectively. Chronotypes are also classified into four types called- the lion, bear, dolphin and the wolf. 

Most studies that comprehend how chronotypes work and affect our circadian rhythms are based on these early and late chronotype variations. While the environment plays a major role, the internal body clock that regulates our sleep and activity cycles also partially influences our chronotype. 

Various studies have shown that having a late chronotype affects mental well-being, sleep loss disorders, improper metabolic functioning. In recent studies, scientists have now shown that the sleep timing of the mother during her last trimester plays a crucial role in her mental wellbeing. 

How can sleep manifest anxiety in pregnant women?

Sleep fragmentation is higher in pregnant women due to hormonal imbalance and physical changes occurring in the body which causes significant sleep loss. As hampered sleep-wake cycles are known to increase anxiety and mood disorders, these factors put pregnant women under high risk for mental instability. 

How does chronotype affect mental state?

Circadian rhythm, which maintains a nearly 24 hour cycle, syncs with the environmental patterns. A person with a late chronotype has heightened activity at the offset of the day. This is not insync with the environmental rhythm and hence affects the internal circadian cycling. 

The internal body clock entrains itself with the environment using environmental cues called zeitgebers, such as light. The body clock is made up of transcriptional-translational feedback loops. These internal autonomous clocks are reset using light which helps adjust to the natural light. Light sensitive proteins, Period 1 and Period 2, are part of the cascade responsible for resetting the light. 

If a light pulse is perceived at night, the clock is affected. Readjusting to this light at an odd time leads to delayed clocks in people having late chronotype and thus, increased sleep drive during the morning hours. However, due to the environmental day-night cycle, lack of peace from the surroundings and increased light during the day may not allow the person to sleep. This lack of consolidated sleep aggravates mental distress.

What effects does chronotype have on pregnancy?

Scientists from Brown University have conducted a study on 51 pregnant women with previously known unipolar or bipolar depression but with no active depression cases. They measured the melatonin levels of these women in the night phase and classified them into early and late sleepers. From this experiment, they found that late sleepers experienced more manic and mood disorders within two weeks post delivery. They also observed that sleep timing of mothers in the third trimester was crucial in postpartum depression. 

The biological reason behind increased anxiety with loss of rhythm has not been identified yet and is currently speculated to be disjointed body and environmental clocks. In an attempt to understand the influence of the circadian clock on mood disorders, scientists conducted experiments analysing different parameters of the clock.

The scientists sampled around 73 women to understand the effects of circadian rhythm other than sleep that plays a role in mood disorders. The women were asked to wear a watch that measures circadian parameters of human beings (actigraphy). The researchers saw that more than sleep, the strength of the circadian rhythm and mean activity during the night greatly influenced the developing anxiety and depression in women. 

How to overcome anxiety during pregnancy?

  1. Improved sleep cycle: Trying to have a consolidated sleep of around 8 hours. Melatonin patches are advised in worse cases. 
  2. Improved sleep timing: Having a stronger circadian rhythm helps reduce anxiety. 
  3. Social help groups: Talking to people and professionals about mental health has shown to be beneficial for people facing mental instability.
  4. Eating habits: Similar to sleep, eating on time is shown to reduce anger and anxiety.
  5. Meditation and Yoga: Multiple means like meditation and yoga practises are available to calm ourselves and manage external stress.

In our society, discussing mental health and related instabilities is still considered a taboo which has to be removed from our system. People should learn to prioritise mental health. This is even more important in pregnant people due to the physical changes that the body undergoes. Every woman should learn about their mental state and opt for timely treatment. 


Aishwarya Segu is a PhD student from IISER Trivandrum who is fascinated with the working of the brain. She is a curious scientist, an avid reader and a trying writer.

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