Circadian rhythms and depression

Your body regulates on a 24 hour cycle that can get messed up when you don’t get enough light or too much light. Find out about your circadian rhythm, and what happens when it is disrupted, including its link to several mental health disorders. Get tips on how to overcome circadian disruption.

Signs this might be a problem…

  • you have a bad sleeping pattern
  • you get tired/depressed in winter
  • you don’t really get much light
Sleeping boy under sheets

What are circadian rhythms?

There’s a section of our brain which synchronises our body to a 24 hour cycle and releases hormones to regulate our regular bodily functions – things like:

  • appetite
  • energy
  • mood
  • sleep

These daily cycles for appetite, sleep, etc. are known as circadian rhythms and they are really important to our physical and emotional wellbeing; they help us to keep a stable mood and good physical health

Your body can usually tell when to prepare for certain events. For example, when the sun comes up your body releases cortisol to give you energy so you can be active during the day, and when the sun goes down, you produce and release melatonin, a hormone which makes you sleepy.

Sometimes these cycles get messed up and that can wreak all sorts of havoc on our physical and emotional health. When our circadian rhythms are disrupted and our bodies produce hormones at the wrong time of day, it can increase the chance of depression or worsen existing depression. For example producing melatonin in the day time can cause us to feel dull, unstable, irritable and moody. 

So, what causes circadian systems to get messed up? 

  • lack of sleep
  • stress
  • trauma
  • going to bed and waking up at strange hours
  • shift work
  • genetic factors
  • lack of light.

Signs and symptoms of circadian disruption

When our circadian rhythms have been disrupted, it can have a range of impacts on our physical and mental health, such as:

  • not being able to feel alert
  • becoming easily agitated
  • feeling slow
  • feeling run down
  • feeling exhausted
  • feeling grumpy and irritable
  • experiencing symptoms of depression.

Other disorders impacted by circadian rhythms

Seasonal Affective Disorder 
Seasonal Affective Disorder (SAD) affects people in winter months when it is darker and colder, particularly in areas of the world that don’t receive much sunlight. When days become shorter and we don’t receive enough light, our brains can miss the cues to produce the right hormones at the right times. This can mean we might be sleepier or more energetic at the wrong time of day.

Bipolar disorder 
Bipolar disorder is different to other types of depression in that it is marked by episodes of unusually elevated mood or mania. These episodes can last for hours, days or even months. In many cases of bipolar disorder, depressive and manic episodes are seasonal.

What to do about circadian disruption

There are a range of things people do to get their circadian schedule back in working order. The first step is to recognise and correct bad habits which could lead to  problems. Make corrections such as:

  • Don't take naps during the day.
  • Allow yourself time to wind down at the end of the day. Check out some ways to relax.
  • Get exposure to sunlight in the mornings.
  • Get into regular sleeping routine – try to go to bed and wake up at the same times each day and night.
  • Eat and exercise regularly.

If this isn't working

Sometimes this isn’t quite enough and a doctor may need to help you with different strategies to kick your cycle back into the right pattern, including: 

  • light therapy – exposure to bright or blue light during the daytime can help your cycle realign 
  • medication

Your doctor will be able to work with you to figure out an approach that suits you and your lifestyle.

What can I do now?

  • Get tips on getting into a good sleeping routine.
  • Try and get up and go to bed at the same time each day, allowing for 8-9 hours sleep each night.
  • Get outside and enjoy the morning sunshine.


Last reviewed: 16 February, 2014
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