Not a diagnosis: a head start. These are the three drivers most worth checking first, based on what the evidence says gets missed most often.
Vitamin D, B12, thyroid, iron and inflammation all produce low mood and are all testable.
Mood and sleep drive each other. Fix the sleep half and the mood half lightens.
A low patch lasting weeks is a GP conversation in itself. That is not weakness; it is data.
Vitamin D, B12, TSH, ferritin, HbA1c
1. Start a two-minute note in the free journal that asks back, so the pattern becomes visible.
2. Take the test list above to your GP; the GP Script Generator will help you say it clearly.
3. Read the evidence: Low Mood vs Depression: When Sadness Is Something More · Vitamin D Deficiency UK: Why 90% Are Low and What It Actually Does.
Want it tracked and reviewed monthly by a real person? The Club, £10/month.
Education, not diagnosis, and never a replacement for your GP or pharmacist. Reference ranges and guidance vary; sudden, severe or worsening symptoms need 111, or 999 in an emergency. By Hussain Sharifi · independent, affiliate-free health intelligence.