Spring and summer seasonal affective disorder (summer depression) Summer-onset seasonal affective disorder symptoms include: * Anxiety * Trouble sleeping (insomnia) * Irritability * Agitation * Weight loss * Poor appetite * Increased sex drive Reverse seasonal affective disorder In some people, spring and summer can bring on symptoms of mania or a less intense form of mania (hypomania). These can include elevated mood, agitation, and rapid thoughts and speech. Reverse seasonal affective disorder is a form of bipolar disorder. Signs and symptoms of reverse seasonal affective disorder include: * Persistently elevated mood * Increased social activity * Hyperactivity * Unbridled enthusiasm out of proportion to the situation
Chris - How do plants detect time? We know humans do it well. We know there are clusters of nerve cells in the brain that have this sort of genetic domino effect which keeps time. How do plants do it? Will grow in the dark but will die, not food/energy; but some can be induced by being give sugar/sucrose. Some of the plants in the forest labSteve - Plants have a localised clock like we do in our brain. Plants have distributed their clock into every cell. For a human, our clock is reset by light entering our eyes. Although this may sound a little creepy there are eyes in every cell of the plant. There are proteins that transmit light to the plant and reset the plant every day. Chris - But plants would be interesting because the ones you’ve got on your shelf here, they have flowers. This means certain bits of this plant know it’s now time for me to make a flower. How does the plant tell one bit of the plant ‘stop growing leaves and start growing modified leaves called flowers’? Steve - It’s a fascinating story. Plants use their leaves to tell daily time and to measure the amount of light that’s around. They combine the measurement of dawn and dusk with an internal timekeeper to actually discriminate day length. These plants that are sitting next to us can actually tell when the days are getting shorter because they’re short-day plants. That will induce flowering. Other plants are long-day plants as they measure the days getting longer they send a signal to the tip of the plant and they start making flowers.
Clockwork Genes: Discoveries in Biological Time Lecture 1 – Biology in Four Dimensions by Joseph S. Takahashi, Ph.D. Howard Hughes Medical Institute