When the clocks go back: your body clock and your mood

When the clocks go back: your body clock and your mood

On 25 October, the clocks in the Netherlands and the rest of Europe went back an hour. You get an extra hour in bed, and from Monday it's dark before dinner. For many people that's a small annoyance. For others, the shorter days bring a dip in mood and energy that hangs around until spring.

The news

The timing fits a study that came out this week. On 21 October, The British Journal of Psychiatry published research from the University of Sydney's Brain and Mind Centre proposing a "circadian" subtype of depression, one tied to a disrupted internal clock.

The team looked at more than 11,000 adults with depression in the Australian Genetics of Depression Study. People counted as having the circadian subtype if they had at least three of six features: social jetlag (a big gap between workday and weekend sleep times), seasonal mood changes, a late sleep midpoint, being an evening type, morning tiredness, and sleeping too much.

About 23% of participants (2,604 people) fit that profile. Their depression tended to start earlier, and they reported more distress, more severe symptoms and more weight gain during episodes. They also said common antidepressants (SSRIs and SNRIs) helped them less and caused more side effects. Their genetic risk scores were higher for depression, anxiety, ADHD and bipolar disorder, and for traits such as insomnia and a late chronotype.

There are limits. The data were collected at one point in time, much of it was self-reported, and it all comes from one Australian cohort. The authors say the subtype needs independent replication before it can guide treatment.

What the research says about light

Seasonal affective disorder (SAD), or winter depression, is the best-known case of mood following the light. A 2024 network meta-analysis of 21 randomised trials with 1,037 participants found that light therapy beat the comparison treatments for SAD, with mild to moderate effects. The authors rated the evidence quality as low and called for larger trials. A 2025 network meta-analysis of 17 trials compared colours of light and found white light worked best.

What about the clock change itself? A 2026 systematic review of 157 studies on daylight saving time found no clear, consistent effects on psychiatric outcomes. So the one-hour jump on Sunday is probably less of a worry than the months of short, dark days that follow it.

What you can do

• Get outside in daylight, ideally in the morning, even when it's grey.

• Keep your sleep and wake times fairly steady, weekends included. Social jetlag was one of the six features in the study.

• Keep moving and keep seeing people, outdoors where you can.

• Pay attention if low mood comes back every autumn. If it lasts more than a couple of weeks or gets in the way of daily life, talk to your GP.

• Light therapy, talking therapy and medication are all options, and a professional can help you choose.

This post is general information, not personal medical advice.