Will using e-reader at bedtime give me sleepless nights?

Is it bad for you to look at a small screen in the evening? I keep hearing it can disturb your sleep.

- Dr Rosemary Leonard

I've always read in bed for half an hour or so, and have switched from books to a Kindle but am now wondering whether this is bad for my health?

Screens emit blue light, a high energy portion of the visible light spectrum. While blue light from sunlight can help to regulate our natural circadian rhythm, or sleepwake cycle, excessive amounts can reduce production of melatonin, a chemical produced in the brain that helps induce sleep.

This in turn can disrupt this natural rhythm and make it more difficult to go to sleep.

Blue light can also make it harder for your eyes to focus and can lead to eye strain and also dry eyes, and for this reason looking at a small screen for long periods, especially in the evenings, is not advisable.

Most modern Kindle devices include blue light filtering features, and lowering the display brightness and using night mode can help to reduce blue light exposure.

Most kindles also use an e-ink display, which mimics the appearance of ink on paper, and this requires less direct light into the eyes, reducing eye strain. However, if you do find you have difficulty getting to sleep, then reading a print book is a better option.

I'm 34 and keep getting a stabbing pain in my back passage, lasting about five minutes. I've had stool tests for blood and inflammation and they were clear. I am prone to being a bit constipated. My doctor advised me to eat more fibre, but it hasn't made any difference. Is there anything else I can do?

This sounds like proctalgia fugax where there is sudden cramping pain in the anus, the lowest part of the large bowel.