Summer sleep can be disrupted by heat and the bright light of earlier mornings.

As if feeling tired wasn't irritating enough, scientists have also found that lack of sleep can make us fat, by slowing our metabolism so the body burns fewer calories. A recent Colorado Boulder University study revealed that we're inclined to snack more if we're sleep deprived too.

But simple measures can ensure a good night's rest, says Dr Neil Stanley, independent sleep expert.

"Sleep problems are common at this time of year as daylight is a signal to our bodies to wake up. So light streaming through the windows at sunrise, around 4am, often coupled with a dawn chorus, can disturb us and wake us earlier than we want.

"Also, warmer temperatures make it harder for us to keep cool in bed and slow the essential process of losing around half a degree of body heat throughout the night. That results in restless, fidgety, interrupted sleep."

His tips for a quieter, calmer night's sleep are:

• Block out light with eyeshades, similar to those provided on air flights.

• Wear cotton nightwear, rather than sleeping naked, as the fabric will wick away sweat from the body and help it to cool down.

• Avoid alcohol and fatty meals late at night as burning calories  raises the body's temperature making it difficult to sleep.

• Try to be positive about early awakenings. Regard them as an opportunity to take exercise or have a more leisurely preparation for work rather than viewing making them a catastrophes.

• If you're getting enough sleep for your body you shouldn't feel sleepy during the day. Ordinary tiredness can be due to all sorts of reasons, but if you're yawning, your sleep quality and quantity probably needs adjusting.