Humans

  1. Health & Medicine

    Explainer: The teenage body clock

    Around puberty, a change in the body clock of adolescents and teens makes it hard for them to fall asleep as early as they used to.

    By Susan Gaidos
  2. Tech

    Sniffing for cancer

    New surgical tool offers surgeons speedier diagnosis of tissues that are cancerous.

    By Stephen Ornes
  3. Health & Medicine

    Cool Jobs: Sports science

    From soccer teams to the balance beam, scientists help athletes perform their best.

    By Helen Fields
  4. Health & Medicine

    Explainer: What should I know about HIV and AIDS?

    Here are some common myths and some less common facts.

    By Bryn Nelson
  5. Microbes

    Some dirt won’t hurt

    It could even lower risks of serious allergic disease.

    By Alison Pearce Stevens
  6. Brain

    Explainer: What is jet lag?

    Traveling across time zones can disrupt circadian rhythms.

    By Amanda Leigh Mascarelli
  7. Life

    Explainer: What is a stem cell?

    Special cells have ability to turn into several different types

    By Alison Pearce Stevens
  8. Health & Medicine

    Fat becomes a disease

    Medical group decides it is time for doctors to view — and treat — obesity as a disease.

    By Janet Raloff
  9. Health & Medicine

    Infection time

    Disease is more severe when it hits in the morning, at least in mice.

    By Stephen Ornes
  10. Brain

    Explainer: Our bodies’ internal clocks

    Biological clocks determine hunger, sleepiness and other daily rhythms.

    By Amanda Leigh Mascarelli
  11. Health & Medicine

    Flu in the air

    Germs tiny enough to pass through surgical masks may cause half of all cases.

    By Stephen Ornes
  12. Health & Medicine

    An itch switch

    Scientists identify a chemical that helps the brain know where to scratch.

    By Stephen Ornes