What is my circadian rhythm?

Most animals and plants have a built-in circadian rhythm, an internal system that in humans regulates feelings of sleepiness and wakefulness over roughly a 24 hour cycle.

Circadian rhythm

Your circadian rhythm causes your level of wakefulness to rise and dip throughout the day. Most people feel the strongest desire to sleep between 1:00pm and 3:00pm and then again between 2:00am and 4:00am, but this can vary from person to person. That’s why some people are “morning people,” while others function best in the evening.

Your circadian rhythm is also known as your sleep/wake cycle or body clock. The study of circadian rhythms is called chronobiology

Your circadian rhythm can change as you age. For example; teenagers sleep for more total hours, as well as going to bed and waking up later.

Hypothalamus

It is controlled by the hypothalamus region of the brain. Your circadian clock checks its accuracy each day using external environmental cues, principally light or darkness. Though it does not actually require light to function and can function quite accurately even when people are completely cut off from daylight.

Sleep routine

Circadian rhythms may be adjusted by up to two hours or so either way according to an individual’s make up. Some people (morning people) tend to wake up early and are most alert during the first part of the day. Others (evening people) are most alert in the late evening and prefer to go to bed late. In these people, the timing of their circadian cycle is shifted; an effect that is at least partly encoded in their genes.

If you follow your body’s natural cues about when to go to sleep and wake up and have a good sleep routine, your circadian rhythm should stay balanced. A change in your schedule can disrupt your body clock, effecting the quality of your sleep.

Author: Emily AttwoodPublished: 8 March 2018Last modified: 13 June 2024

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Bedding size guide

Duvet sizes

These are standard UK bedding measurements so if you know your mattress size, you can easily work out which duvet size you need. (Width x length.)

UK sizes	Duvet size	Mattress size
Single	135 x 200cm (53 x 79")	90 x 190cm (36 x 75")
Double	200 x 200cm (79 x 79")	135 x 190cm (53 x 75")
King	225 x 220cm (89 x 87")	150 x 200cm (60 x 78")
Super king	260 x 220cm (102 x 87")	180 x 200cm (72 x 78")

European bedding sizes: Each size - Single, Double, King and Grand king - is a little larger than the UK equivalent.

Measure your mattress to see which size bedding you need: our UK v European v US mattress comparison guide.

Duvet tog ratings

Young children can overheat so if they are old enough to use a full size bed, we recommend using a single size 4.5 tog duvet.

Tog rating	Season / heat	Feel
2.5 tog	High summer / hot sleepers	Light thermal insulation
4.5 tog	Summer	Lower thermal insulation
9 tog	Spring & Autumn	Cosy medium heat
All season 13.5 tog	4.5 tog + 9 tog	Very warm
All season 11.5 tog	2.5 tog + 9 tog	Warm
All season 7 tog	2.5 tog + 4.5 tog	Lower warmth

Duvet fill weights

Our goose down duvets have high 700 fill power. Fill weight is measured in GSM (grams per square metre). For example view our 9 tog king size goose down duvet for more duvet details.

	Fill weight (not total duvet weight)
Single	All seasons - 788gsm 9 tog - 486gsm 4.5 tog - 302gsm 2.5 tog - 220gsm
Double	All seasons - 1168gsm 9 tog - 720gsm 4.5 tog - 448gsm 2.5 tog - 320gsm
King	All seasons - 1478gsm 9 tog - 911gsm 4.5 tog - 567gsm 2.5 tog - 400gsm
Super king	All seasons - 1671gsm 9 tog - 1030gsm 4.5 tog - 641gsm 2.5 tog - 480gsm

Pillow sizes

Our pillows come in two sizes and two firmness options. (Width x length.)

Standard	50 x 75cm
King	50 x 90cm

Bed linen sizes

Our fitted sheets are deep fit, up to 40cm / 15.7" mattress depth. And our duvet covers fasten with large, easy to use buttons. (Width x length.)

	Duvet cover	Fitted sheet	Flat sheet	Pillowcase (pair)
Single	140 x 200cm	90 x 190cm	180 x 275cm
Double	200 x 200cm	135 x 190cm	230 x 275cm	50 x 75cm (Standard)
King	230 x 220cm	150 x 200cm	275 x 275cm	50 x 90cm (King)
Super king	260 x 220cm	180 x 200cm	305 x 275cm

Topper & mattress protector sizes

Our mattress protectors are deep fit, up to 40cm mattress depth. Choose the same size topper or protector as your mattress size. (Width x length.)

	Topper / protector size	Mattress size
Single	90 x 190cm	90 x 190cm
Double	135 x 190cm	135 x 190cm
King	150 x 200cm	150 x 200cm
Super king	180 x 200cm	180 x 200cm

US/CANADA BEDDING SIZES: Approximate matches to UK sizes are US King/UK Super king, US Queen/UK King, US Full/UK Double and US Twin/UK Single.

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