What your sleep pattern can tell us

Describing the whole day

Someone can spend eight hours in bed and still find getting through the morning difficult. They may feel more alert late at night, struggle to wake for work and sleep at quite different times when there is no alarm to answer. When low mood is also present, a question about how many hours they sleep can leave much of that experience unexplained.

I would want to hear what happens across an ordinary day, including when the person begins to feel sleepy, what waking is like and how their energy changes afterwards. I would also ask whether this pattern is longstanding or began around a period of depression, a change in medication or a new roster. The same late bedtime can mean different things for someone working evening shifts and someone lying awake worrying about the next morning.

These details need to sit alongside the circumstances in which sleep happens. Caring for a young child, persistent pain, an unsafe home or work that starts before dawn can leave very little choice about rest. A conversation that begins with instructions to become more disciplined may miss the practical problem and make it harder for the person to explain what their nights are like.

What the Australian study found

Tonini and colleagues' study, published in the British Journal of Psychiatry in October 2026, examined 11,380 adults from the Australian Genetics of Depression Study. The researchers grouped participants using six sleep and circadian features, including evening preference, morning tiredness and differences in sleep timing between working and free days. About 23 per cent met their provisional definition of a circadian profile.

People in that group reported earlier depression onset, greater psychological distress and lower perceived benefit from some commonly prescribed antidepressants. The researchers were examining associations in existing survey and genetic data. They did not assign people to treatments or test whether changing sleep timing improved depression.

The classification remains exploratory. Participants recalled much of their history, the analysis included only people of European ancestry, and the study did not directly measure the body's circadian timing. Its selected sample also included many people with recurrent depression. We cannot use the 23 per cent figure as an estimate for everyone experiencing low mood, or use a familiar sleep pattern to diagnose a new subtype.

For me, the useful clinical question is whether we have described sleep closely enough to understand the person's difficulties and plan further assessment. I would be cautious about changing treatment because someone recognised themselves in a description of this research, especially if it led them to stop medication that had been helping.

How sleep treatment fits into the picture

There is separate evidence that treating insomnia can have benefits for mood. In a randomised trial reported by Irwin and colleagues in JAMA Psychiatry, 291 adults aged 60 and over received either cognitive behavioural therapy for insomnia or sleep education. They had insomnia but had not experienced major depression within the preceding year. Over follow-up of up to three years, a new or recurrent episode of major depression occurred in about 12 per cent of the therapy group and 26 per cent of the education group.

That was a structured treatment involving several components, so the result cannot be reduced to advice about keeping a regular bedtime. The study was conducted at one US site with predominantly White older adults, and many participants did not complete the full three-year follow-up. It gives us evidence about depression prevention in that particular group, while leaving open how best to treat the circadian profile proposed in the newer Australian study.

In an individual assessment, I would want to distinguish difficulty falling or staying asleep from a sleep schedule that conflicts with work or family demands, while allowing for both to be present. Persistent tiredness can also warrant medical assessment, particularly when there is snoring, disturbed breathing or marked daytime sleepiness. A psychological formulation needs to remain open to problems that require a different kind of care.

Bringing the pattern into an appointment

If you are arranging an appointment about low mood, a brief account of a working day and a day off may be useful. Include roughly when you go to bed, when you think you fall asleep and when you wake, along with any naps and how you feel through the morning. You can describe what you remember without buying a device or producing a perfectly completed diary.

I would also be interested in what gets in the way of the sleep you want. Perhaps late evening is the only time that feels like your own, or you remain in bed because the coming day feels difficult to face. Those possibilities lead to different conversations, and neither should be assumed from the time on the clock. Where work or caring responsibilities set the schedule, we would need to consider what can realistically change and who else may need to be involved.

Any plan should be reviewed against how you are functioning, including whether mornings become more manageable and whether mood changes. If keeping detailed sleep records makes you more preoccupied with getting sleep right, tell your clinician so that the approach can be adjusted. Decisions about medication, melatonin or bright-light treatment belong in an individual discussion with an appropriately qualified clinician, particularly if there have been periods of unusually high energy with little need for sleep.

You can bring this up even if therapy is already under way. Describing a recent week, including the differences between days with obligations and days without them, gives your psychologist and GP something concrete to assess alongside your mood and current treatment.