Cut your light at night (3/9/11)
Light is a Drug
If reading this at night, you might want to dim the lights.
Q: What is the drug everyone is sensitive to?
A: Light. (Some, but not all blind people are exceptions – more below)
Q:What does it do?
A: Change body clocks; in the daytime improve mood and create vitamin D; shift immunity, increase natural killer cell activity.
So what does light do just before sleep?
The National Sleep Foundation just surveyed Americans aged 13-64 about their sleep, and the results were not encouraging. Sixty three percent said they had trouble sleep many or most nights. This is in accord with the recent CDC study of 75,000 adults, including older individuals, demonstrating over a third slept less than 7 hours on average each night.
Americans are sleepless. Is light at night one of the reasons?
In the NSF survey, a full 95% of the population many or most nights was using electronics with light expsosure before sleep – either through televisions, computers, cell phones, or tablets. This light is often much more powerful than people appreciate. Many sleep docs think night light is unhelpful before sleep because:
- Late night light keeps people up and keeps them more alert.
- Late night light resets biological clocks to later in the night – making many, particularly adolescents, go to bed later and later.
- Late night light turns off melatonin production.
- People who have more late night light seem to have higher risk of severe disease – one Israeli group found higher rates of breast cancer.
- Late night light clearly violates normal body clocks – putting them out of synch and possibly leading to systemic immunological difficulties.
If light is a drug, then how do you properly use it?
Light at Night
Though nothing succeeds like excess, too much light, especially sunlight, is problematic. Positively, daytime sunlight increases vitamin D and natural killer cell levels. And despite the risks of increased skin cancers, other tumors may become rarer through exposure to sunlight. One Australian study of prostate cancer, that supposedly controlled for exercise level and other illnesses, found half the expected incidence among men who worked regularly outside.
Yet light at night is a different animal. As shift workers can tell you, changing body clocks causes malfunctions almost everywhere. Shift workers have more heart disease, more strokes, probably more tumors, and certainly more mood problems.
If light at night can provoke these kinds of problems, why bring them on yourself?
In order to sleep you first need to rest. So if you can:
- Make the lights at night dim – especially in the hour before you fall asleep.
- If possible, turn off electronic devices an hour before you go to bed. The light they pump out will keep you up longer and may well interfere with sleep.
- Rest before sleep – read, do yoga, put out the clothes you will wear the next day. Get your mind relaxed and focused on things that help you feel calm, rather than rev you up.
- Take out an eye mask if your light exposure at night is too high to let you rest. We can appreciate a tiny amount of light even through firmly closed eyes. We also have light receptors in our eyes that are non-visual, and are used to reset our long term biological clocks. About half of blind people still appear to have these retinal giant cells that literally place your body in time, allowing your brain to schedule the many physiologic changes of the 24 hour day.
- Simply recognize that light is a drug. You want to use it during the day. It can alert you, wake you, encourage you.
But you don’t want so much light at night – especially before sleep. Our bodies are built on time. Our times for required rest are decreed by our planet’s motion around the sun.
Darkness has its uses, after all.
Rest, sleep, Sarasota Sleep Doctor, well-being, regeneration, longevity, body clocks, insomnia, sleep disorders, the rest doctor, matthew edlund, the power of rest, the body clock, psychology today, huffington post, redbook, longboat key news