SHORT ANSWER
Sleep and mood are connected in both directions: persistent insomnia intensifies anxiety and low mood, while depression and anxiety disrupt sleep. If bad sleep lasts weeks — that is a reason for a conversation with a specialist, not just advice to "just get some sleep".
Why is that?
Why the connection is so tight: during sleep the brain "processes" the day's emotions; sleep deprivation raises amygdala reactivity (the fear centre) and weakens prefrontal cortex control — that is why after sleepless nights emotions are sharper, irritability higher, and anxious thoughts spin faster. Conversely: in depression and anxiety the mechanisms of falling asleep and maintaining sleep are disrupted, so "just try to fall asleep" usually does not work — it is not a willpower issue.
Why sleep is a diagnostic marker: sleep disturbances are part of the criteria for both depression and anxiety disorders; persistent insomnia often precedes or accompanies an exacerbation. If you have been sleeping less than 5–6 hours for weeks or wake up exhausted — that is a signal to assess not just your "routine" but your overall state.
What actually helps: a regular wake-up time (including weekends), minimal screens in the hour before sleep, daytime movement, no evening caffeine; if insomnia lasts more than 2–3 weeks or hopelessness is nearby — see a specialist.
WHAT TO DO
- Record for a week: bedtime and wake time, how much you actually sleep, what prevents falling asleep.
- Introduce one rule at a time (for example, only waking up at the same time) — "a routine starting Monday" usually fails.
- Weeks of insomnia + low mood or anxiety = conversation with a specialist; this is not weakness but part of treatment.