For seasonal allergies, the general sense is that one goes to bed feeling miserable and wakes up feeling miserable. Feelings of daytime fatigue and impaired memory--common signs of poor sleep-- increase, leading some to question their sleep quality.
However, in cognitive tests allergy sufferers' performance did not differ significantly from that of non-allergy suffers, leading some to conclude that sleep is not affected by allergies. Subsequent studies have yielded similar results.
One possible explanation is that allergy sufferers may focus on how uncomfortable they feel as a result of their allergies, which can indirectly affect how they view their sleep. Another possibility is that grogginess associated with some allergy medicines can cause people to think that they are not getting restful sleep.
That said, studies have shown a higher instance of sleep apnea among some allergy sufferers. If you suspect your tiredness is something more than allergy-related fatigue, consult your doctor.
Colds are a different story. Not surprisingly, a cold disrupts body's sleep cycle. But did you know that this increase in sleep disruption could actually help fight the virus?
A fever is often a common symptom of some types of viral colds and infections. The elevated temperatures of a fever make the body a less hospitable place for an infection to thrive. Shivering helps the body to maintain this higher temperature—the more your muscles work, the warmer you are. However, because of normal sleep paralysis associated with the REM phase, the body typically does not shiver during REM sleep. In order to more effectively fight back against cold viruses and infections, the body appears to actively suppress REM sleep when simultaneously fighting a cold.
Scientists agree that more research is needed to better understand all the ways sleep and cold viruses interact. For the time being, make sure to follow your doctor's orders when treating a cold.
Here's the silver lining to the sleep-cold story: Getting more sleep can keep the colds away. Research has found a noticeable increase in disease susceptibility among those who got less than seven hours of sleep. Sleep is critical to healthy immune function, and has been shown to improve the effectiveness of vaccines. Considering that most adults have 2-3 colds a year (kids get 6-8), getting enough sleep on a regular basis could be one of the easiest ways to avoid getting sick. Getting enough sleep is a daily investment in your ongoing good health.
Note: S+ is not a medical device. If you are seeking information on how to treat a sleep disorder, you should talk to your healthcare provider.