Exercising before bed has long been discouraged as the body doesn’t have time to wind down before the lights go out.

But new research has found breaking up a quiet, sedentary evening of watching television with short bursts of resistance exercise can lead to longer periods of sleep.

Adults spend almost one third of the 24-hour day sleeping. But the quality and length of sleep can affect long-term health. Sleeping too little or waking often in the night is associated with an increased risk of heart disease and diabetes.

Physical activity during the day can help improve sleep. However, current recommendations discourage intense exercise before going to bed as it can increase a person’s heart rate and core temperature, which can ultimately disrupt sleep.

Nighttime habits

For many, the longest period of uninterrupted sitting happens at home in the evening. People also usually consume their largest meal during this time (or snack throughout the evening).

Insulin (the hormone that helps to remove sugar from the blood stream) tends to be at a lower level in the evening than in the morning.

Together these factors promote elevated blood sugar levels, which over the long term can be bad for a person’s health.

Our previous research found interrupting evening sitting every 30 minutes with three minutes of resistance exercise reduces the amount of sugar in the bloodstream after eating a meal.

But because sleep guidelines currently discourage exercising in the hours before going to sleep, we wanted to know if frequently performing these short bursts of light activity in the evening would affect sleep.

Activity breaks for better sleep

In our latest research, we asked 30 adults to complete two sessions based in a laboratory.

During one session the adults sat continuously for a four-hour period while watching streaming services. During the other session, they interrupted sitting by performing three minutes of body-weight resistance exercises (squats, calf raises and hip extensions) every 30 minutes.

After these sessions, participants went home to their normal life routines. Their sleep that evening was measured using a wrist monitor.

Our research found the quality of sleep (measured by how many times they woke in the night and the length of these awakenings) was the same after the two sessions. But the night after the participants did the exercise “activity breaks” they slept for almost 30 minutes longer.

Identifying the biological reasons for the extended sleep in our study requires further research.

But regardless of the reason, if activity breaks can extend sleep duration, then getting up and moving at regular intervals in the evening is likely to have clear health benefits.

Time to revisit guidelines

These results add to earlier work suggesting current sleep guidelines, which discourage evening exercise before bed, may need to be reviewed.

As the activity breaks were performed in a highly controlled laboratory environment, future research should explore how activity breaks performed in real life affect peoples sleep.

We selected simple, body-weight exercises to use in this study as they don’t require people to interrupt the show they may be watching, and don’t require a large space or equipment.

If people wanted to incorporate activity breaks in their own evening routines, they could probably get the same benefit from other types of exercise. For example, marching on the spot, walking up and down stairs, or even dancing in the living room.

The key is to frequently interrupt evening sitting time, with a little bit of whole-body movement at regular intervals.

In the long run, performing activity breaks may improve health by improving sleep and post-meal blood sugar levels. The most important thing is to get up frequently and move the body, in a way the works best for a person’s individual household.

Jennifer Gale, PhD candidate, Department of Human Nutrition, University of Otago and Meredith Peddie, Senior Lecturer, Department of Human Nutrition, University of Otago

This article is republished from The Conversation under a Creative Commons license. Read the original article.

When we start to go grey depends a lot on genetics.

Your first grey hairs usually appear anywhere between your twenties and fifties. For men, grey hairs normally start at the temples and sideburns. Women tend to start greying on the hairline, especially at the front.

The most rapid greying usually happens between ages 50 and 60. But does anything we do speed up the process? And is there anything we can do to slow it down?

You’ve probably heard that plucking, dyeing and stress can make your hair go grey – and that redheads don’t. Here’s what the science says.

What gives hair its colour?

Each strand of hair is produced by a hair follicle, a tunnel-like opening in your skin. Follicles contain two different kinds of stem cells:

• keratinocytes, which produce keratin, the protein that makes and regenerates hair strands
• melanocytes, which produce melanin, the pigment that colours your hair and skin.

There are two main types of melanin that determine hair colour. Eumelanin is a black-brown pigment and pheomelanin is a red-yellow pigment.

The amount of the different pigments determines hair colour. Black and brown hair has mostly eumelanin, red hair has the most pheomelanin, and blonde hair has just a small amount of both.

So what makes our hair turn grey?

As we age, it’s normal for cells to become less active. In the hair follicle, this means stem cells produce less melanin – turning our hair grey – and less keratin, causing hair thinning and loss.

As less melanin is produced, there is less pigment to give the hair its colour. Grey hair has very little melanin, while white hair has none left.

Unpigmented hair looks grey, white or silver because light reflects off the keratin, which is pale yellow.

Grey hair is thicker, coarser and stiffer than hair with pigment. This is because the shape of the hair follicle becomes irregular as the stem cells change with age.

Interestingly, grey hair also grows faster than pigmented hair, but it uses more energy in the process.

Can stress turn our hair grey?

Yes, stress can cause your hair to turn grey. This happens when oxidative stress damages hair follicles and stem cells and stops them producing melanin.

Oxidative stress is an imbalance of too many damaging free radical chemicals and not enough protective antioxidant chemicals in the body. It can be caused by psychological or emotional stress as well as autoimmune diseases.

Environmental factors such as exposure to UV and pollution, as well as smoking and some drugs, can also play a role.

Melanocytes are more susceptible to damage than keratinocytes because of the complex steps in melanin production. This explains why ageing and stress usually cause hair greying before hair loss.

Scientists have been able to link less pigmented sections of a hair strand to stressful events in a person’s life. In younger people, whose stems cells still produced melanin, colour returned to the hair after the stressful event passed.

4 popular ideas about grey hair – and what science says

1. Does plucking a grey hair make more grow back in its place?

No. When you pluck a hair, you might notice a small bulb at the end that was attached to your scalp. This is the root. It grows from the hair follicle.

Plucking a hair pulls the root out of the follicle. But the follicle itself is the opening in your skin and can’t be plucked out. Each hair follicle can only grow a single hair.

It’s possible frequent plucking could make your hair grey earlier, if the cells that produce melanin are damaged or exhausted from too much regrowth.

2. Can my hair can turn grey overnight?

Legend says Marie Antoinette’s hair went completely white the night before the French queen faced the guillotine – but this is a myth.

Melanin in hair strands is chemically stable, meaning it can’t transform instantly.

Acute psychological stress does rapidly deplete melanocyte stem cells in mice. But the effect doesn’t show up immediately. Instead, grey hair becomes visible as the strand grows – at a rate of about 1 cm per month.

Not all hair is in the growing phase at any one time, meaning it can’t all go grey at the same time.

3. Will dyeing make my hair go grey faster?

This depends on the dye.

Temporary and semi-permanent dyes should not cause early greying because they just coat the hair strand without changing its structure. But permanent products cause a chemical reaction with the hair, using an oxidising agent such as hydrogen peroxide.

Accumulation of hydrogen peroxide and other hair dye chemicals in the hair follicle can damage melanocytes and keratinocytes, which can cause greying and hair loss.

4. Is it true redheads don’t go grey?

People with red hair also lose melanin as they age, but differently to those with black or brown hair.

This is because the red-yellow and black-brown pigments are chemically different.

Producing the brown-black pigment eumelanin is more complex and takes more energy, making it more susceptible to damage.

Producing the red-yellow pigment (pheomelanin) causes less oxidative stress, and is more simple. This means it is easier for stem cells to continue to produce pheomelanin, even as they reduce their activity with ageing.

With ageing, red hair tends to fade into strawberry blonde and silvery-white. Grey colour is due to less eumelanin activity, so is more common in those with black and brown hair.

Your genetics determine when you’ll start going grey. But you may be able to avoid premature greying by staying healthy, reducing stress and avoiding smoking, too much alcohol and UV exposure.

Eating a healthy diet may also help because vitamin B12, copper, iron, calcium and zinc all influence melanin production and hair pigmentation.

Theresa Larkin, Associate Professor of Medical Sciences, University of Wollongong

This article is republished from The Conversation under a Creative Commons license. Read the original article.